Laser-decomposable resin composition and laser-decomposable pattern-forming material and flexographic printing plate precursor of laser engraving type using the same

ABSTRACT

A laser-decomposable resin composition of the invention contains a polyurethane resin having a structure wherein an aromatic group is directly connected to a urethane bond.

FIELD OF THE INVENTION

The present invention relates to a laser-decomposable resin composition,more particularly to a resin composition satisfying both highdecomposability enabling engraving with laser and preservationstability, and a laser-decomposable pattern-forming material andflexographic printing plate precursor of laser engraving type using thesame.

BACKGROUND OF THE INVENTION

Decomposable resins and decomposable resin compositions means resinsdecomposable in response to an external factor, for example, a thermalfactor, a mechanical factor, a photochemical factor, aradiation-chemical factor or a factor with a chemical agent and are wellknown. Change in he form (liquefaction or vaporization) or change in thenature or property, for example, molecular weight, hardness,viscoelasticity, glass transition point (Tg), solubility or adhesivenessof the resin or resin composition before and after the decomposition,which is caused by the decomposition of resin, is utilized in variousfields.

Examples of the decomposable resin and decomposable resin compositioninclude a biodegradable plastic (for example, polylactic acid) fordecreasing environmental impact of plastic material and a slow releasingmaterial which can gradually release a component, for example, medicalagent or fragrance in the field of healthcare, cosmetic or life science.However, they gradually decompose by oxygen, light or enzyme in anatural environment, within the living body, in the soil or the like andthus they do not stably maintain their initial states and can not induceat once a large change in the nature upon the external stimulation.

Resins which are decomposed by light or heat for improvement in therecycling efficiency or simplification of the disposal and adhesiveswhich decrease the adhesiveness thereof are also developed. Further, itis known that ceramic or carbon fiber is mixed with a decomposable resinand then the decomposable resin is removed, for example, by calcinationto form a porous material. However, in these cases, the materials arealtogether treated or processed and it is not intended to form thedesired pattern only in the desired portion. Also, large energy isrequired for the decomposition treatment.

With respect to the application to image formation, for instance, it isknown that both preservation stability and image fixability of toner areachieved by utilizing change in the nature due to heat at theheat-fixing of the toner containing a heat-decomposable resin. However,the resin per se does not have sufficient response to the pattern-wisestimulation.

As for pattern-forming materials, on the other hand, for example, aso-called chemically-amplified resist is well known as a photoresist.Specifically, a composition containing an acid generator and anacid-decomposable resin is pattern-wise exposed followed by heattreatment if desired, to decompose pattern-wise the resin and thepattern is formed with development processing. Although the compositionsatisfies both the preservation stability and the pattern-formingproperty at a practical level, the development process in which theprocessing conditions are fully controlled is indispensable for theformation of pattern. Further, the pattern-formation in a thick layerhaving, for example, several tens of micrometers or more is difficult,though it is possible to apply to at layer.

A method of forming an image utilizing a step of removing (ablation) apart of thin layer by imagewise irradiation of laser beam is also known(JP-A-10-119436 (the term “JP-A” as used herein means an “unexaminedpublished Japanese patent application”)). However, the compounds recitedas the heat-decomposable resin are only conventional general-purposeresins, for example, polyesters, polycarbonates or polyurethanes, andthe thickness of the layer is only around 1 to 2 μm. It is also know touse a compound defined its heat decomposability (JP-A-10-244751).However, the thickness of the layer described therein is also onlyaround 1 to 2 μm.

As a mask material for paste printing to a printed circuit board or thelike, a mask for forming a pattern having approximately 100 to 200 μmutilizing a photo-decomposable resin sheet and a production method ofthe mask are described (JP-A-8-258442). However, a specific compounddoes not disclosed in the patent. Also, the controlled developmentprocessing is indispensable in order to form the pattern whileregulating the degree of exposure and development.

On the other hand, in order to form a pattern in a thick layer by asimple process, for example, pattern-formation by laser processing isknown, in which the base material per se is removed, deformed ordiscolored by imagewise irradiation of laser beam. For instance, amethod of recording information, for example, a lot number on a product(for example, video tape or home electric appliances) composed of avariety of base materials as utilized as a laser maker. In such cases,conventional resins are used as they are as the base material.

In the pattern-formation by laser processing, it is desired that a laserengraving portion (concave portion) be rapidly formed. For this purpose,a high-sensitive laser-decomposable resin composition and ahigh-sensitive laser-decomposable pattern-forming material is needed.

In particular, in case of a flexographic printing plate precursor of adirect drawing type by laser (so-called flexographic printing plateprecursor for laser engraving), since ease of engraving by laser beam(engraving sensitivity) dominates plate-making speed, a flexographicprinting plate precursor for laser engraving using a high-sensitivelaser-decomposable resin composition has been required.

On the other band, a photopolymerizable composition containing apolyurethane resin and a lithographic printing plate precursor for laserscanning exposure using the photopolymerizable composition in aphotopolymerizable photosensitive layer are known (JP-A-11-352691(corresponding to U.S. Pat. No. 6,727,044) and P-A-2001-117229). Thepolyurethane resin functions there as a binder of the photopolymerizablecomposition or photopolymerizable photosensitive layer and it does notdecompose by the laser scanning exposure.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a laser-decomposableresin composition having high sensitivity. Another object of theinvention is to provide a laser-decomposable pattern-forming materialhaving high sensitivity. A further object of the invention is to providea flexographic printing plate precursor of laser engraving type havinghigh sensitivity.

As a result of the extensive investigations, the inventor has found thatby incorporating a polyurethane resin having a structure wherein anaromatic group is directly connected to a urethane bond into alaser-decomposable resin composition, the resin composition is easilydecomposed by laser irradiation to complete the invention. Specifically,the above-described objects can be achieved by the followingconstitutions.

(1) A laser-decomposable resin composition comprising a polyurethaneresin having a structure wherein an aromatic group is directly connectedto a urethane bond.

(2) The laser-decomposable resin composition as described in (1) above,wherein the polyurethane resin is a polyurethane resin including aurethane bond represented by the following formula (1):

In formula (1), R₁ and R₂ each independently represents a divalentorganic group, provided that at least one of R₁ and R₂ is an aromaticgroup.

(3) The laser-decomposable resin composition as described in (2) above,wherein R₂ in formula (1) represents an aromatic group.

(4) The laser-decomposable resin composition as described in (2) above,wherein R₁ and R₂ in formula (1) each represents an aromatic group.

(5) The laser-decomposable resin composition as described in any one of(1) to (4) above, wherein the polyurethane resin further has a carbonatesite.

(6) The laser-decomposable resin composition as described in any one of(1) to (4) above, wherein the polyurethane resin further has an acetalsite.

(7) The laser-decomposable resin composition as described in any one of(1) to (6) above which further comprises a polymerizable compound.

(8) The laser-decomposable resin composition as described in any one of(1) to (7) above which further comprises a binder polymer.

(9) A laser-decomposable resin composition prepared by curing thelaser-decomposable resin composition as described in (7) above.

(10) A laser-decomposable resin composition prepared by curing thelaser-decomposable resin composition as described in (8) above.

(11) A pattern-forming material comprising a support and aheat-decomposable resin layer comprising the laser-decomposable resincomposition as described in any one of (1) to (7) and (9) above.

(12) A pattern-forming material comprising a support and aheat-decomposable resin layer comprising the laser-decomposable resincomposition as described in (8) or (10) above.

(13) A laser-decomposable pattern-forming material comprising a supporthaving thereon at least two heat-decomposable resin layers wherein aresin constituting the heat-decomposable resin layer close to thesupport is a polyurethane resin having a structure wherein an aromaticgroup is directly connected to a urethane bond.

(14) The laser-decomposable pattern-forming material as described in(13) above, wherein heat decomposition temperature of a resinconstituting the heat-decomposable resin layer positioned above theheat-decomposable resin layer close to the support is higher Man heatdecomposition temperature of the polyurethane resin having a structurewherein an aromatic group is directly connected to a urethane bond.

(15) The laser-decomposable pattern-forming material as described in(13) or (14) above, wherein the polyurethane resin is a polyurethaneresin including a urethane bond represented by the following formula(1):

In formula (1), R₁ and R₂ each independently represents a divalentorganic group, provided that at least one of R₁ and R₂ is an aromaticgroup.

(16) The laser-decomposable pattern-forming material as described in(15) above, wherein K₂ in formula (1) represents an aromatic group.

(17) The laser-decomposable pattern-forming material as described in(15) above, wherein R₁ and R₂ in formula (1) each represents aromaticgroup.

(18) The laser-decomposable pattern-forming material as described in anyone of (13) to (17) above, wherein the polyurethane resin further has acarbonate site.

(19) A flexographic printing plate precursor of laser engraving typecomprising the laser-decomposable pattern-forming material as describedin any one of (11) to (18) above.

By using the laser-decomposable resin composition according to thepresent invention, a laser-decomposable pattern-forming material havinghigh sensitivity, particularly, a flexographic printing plate precursorof laser engraving type having high sensitivity, is obtained and laserengraving can be conducted in high sensitivity to easily form a pattern.

DETAILED DESCRIPTION OF THE INVENTION

The laser-decomposable resin composition according to the invention willbe described in more detail below.

The laser-decomposable resin composition according to the inventioncomprises a polyurethane resin having a structure wherein an aromaticgroup is directly connected to a urethane bond.

First, the polyurethane resin having a structure wherein an aromaticgroup is directly connected to a urethane bond is described below.

The polyurethane resin having a structure wherein an aromatic group isdirectly connected to a urethane bond (hereinafter, also referred to asa specific polyurethane resin) means that at least one of a diisocyanatecompound and a diol compound for use i the production thereof containsan aromatic group. Specifically, it is a resin obtained by using as astarting material, an aromatic diisocyanate compound and/or an aromaticdiol compound in the production of the polyurethane resin.

Of the polyurethane resins having a structure wherein an aromatic groupis directly connected to a urethane bond, a polyurethane resin includinga urethane bond represented by formula (1) shown below is particularlypreferable.

In formula (1), R₁ and R₂ each independently represents a divalentorganic group, provided that at least one of R₁ and R₂ is an aromaticgroup.

The aromatic group described in formula (1) is not particularlyrestricted and from the standpoint of ease of synthesis, a phenylenegroup which may have a substituent or a naphthylene group which may havea substituent is preferable. In particular, a phenylene group which mayhave a substituent is preferable. Especially, a phenylene groupsubstituted with an electron withdrawing substituent, for example, acarbonyl group, a halogen atom or a nitro group is preferable.

The basic skeleton of the specific polyurethane resin according to theinvention is described below. The specific polyurethane resin is apolyurethane resin comprising as the basic skeleton, a structural unitbased on a reaction product of at least one diisocyanate compoundrepresented by formula (4) shown below and at least one diol compoundrepresented by formula (5) shown below.OCN—X⁰—NCO   (4)HO—Y⁰—OH   (5)

In formulae (4) and (5), X⁰ and Y⁰ each independently represents adivalent organic residue, provided that at least one of the organicresidues represented by X⁰ and Y⁰ is connected to the NCO group or theOH group with an aromatic group.

(i) Diisocyanate Compound

In the diisocyanate compound represented by formula (4), it ispreferable that the organic residue represented by X⁰ has an aromaticgroup directly connected the NCO group.

Preferable examples of the diisocyanate compound include a diisocyanatecompound represented by the following formula (6):OCN-L¹-NCO   (6)

In formula (6), L¹ represents a divalent aromatic hydrocarbon groupwhich may have a substituent. Examples of the substituent include analkyl group, an aralkyl group, an aryl group, an alkoxy group, anaryloxy group and a halogen atom (e.g., —F, —Cl, —Br or —I). If desired,L¹ may contain other functional group which does not react with theisocyanate group, for example, an ester group, a urethane group, anamido group or a ureido group.

Specific examples of tie diisocyanate compound represented by formula(6) include the following compounds. Specifically, an aromaticdiisocyanate compound, for example, 2,4-tolylene diisocyanate, dimer of2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-xylylenediisocyanate, m-xylylene diisocyanate, 4,4′-diphenylmethanediisocyanate, 1,5-naphthylene diisocyanate or3,3,-dimethylbiphenyl-4,4′-diisocyanate is exemplified.

From the standpoint of heat decomposability, 4,4′-diphenylmethanediisocyanate or 1,5-naphthylene diisocyanate is particularly preferable.

In the specific polyurethane resin used in the invention, a diisocyanatecompound other than the above-described diisocyanate compound may beused together in view of, for example, increase in compatibility withother components in the laser-decomposable resin composition andimprovement in preservation stability.

For example, an aliphatic diisocyanate compound, for example,hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysinediisocyanate or dimeric acid diisocyanate; an alicyclic diisocyanatecompound, for example, isophorone diisocyanate,4,4′-methylenebis(cyclohexyl isocyanate), methylcyclohexane-2,4(or2,6)-diisocyanate or 1,3-(isocyanatomethyl)cyclohexane; and adiisocyanate compound obtained by a reaction of diol with diisocyanate,for example, an adduct of I mole of 1,3-butylene glycol and 2 moles oftolylene diisocyanate are exemplified.

Also, a diisocyanate compound obtained by adding a monofunctionalalcohol to one of three NCO groups of triisocyanate can be used.

(2) Diol Compound

In the diol compound represented by formula (5), it is preferable thatthe organic residue represented by Y⁰ has an aromatic group directlyconnected to the OH group.

Specifically, diol compounds represented by formulae (A-1) to (A-3)shown below are preferable.HO—Ar¹—OH   (A-1)HO—(Ar¹—Ar)_(m)—OH   (A-2)HO—Ar¹—X—Ar²—OH   (A-3)

In the formulae, Ar¹ and Ar², which may be the same or different, eachrepresents an aromatic ring. Examples of the aromatic ring include abenzene ring, a naphthalene ring, an anthracene ring, a pyrene ring anda heterocyclic ring. The aromatic ring may have a substituent. Examplesof the substituent include an alkyl group, an aralkyl group, an arylgroup, an alkoxy group, an aryloxy group and a halogen atom (e.g., —F,—Cl, —Br or —I).

From the standpoint of availability of raw materials, a benzene ring ora naphthalene ring is preferable. Taking also the film-forming propertyinto under consideration, a benzene ring is particularly preferable.

X represents a divalent organic residue. m is preferably from 1 to 3from the standpoint of the film-forming property, and particularlypreferably 1.

Preferable examples of e diol compound represented by formula (A-1)include 1,4-dihydroxybenzene and 1,8-dihydroxynaphthalene.

Preferable examples of the diol compound represented by formula (A-2)include 4,4′-dihydroxybiphenyl and 2,2′-dihydroxybinaphthyl.

Preferable examples of the diol compound represented by formula (A-3)include bisphenol A and 4,4′-bis(hydroxyphenyl)methane.

In the specific polyurethane resin used in the invention, a diolcompound other the above-described diol compound may be used together inview of for example, increase in compatibility with other components inthe laser-decomposable resin composition and improvement in preservationstability.

Such a diol compound includes, for example, a polyetherdiol compound, apolyesterdiol compound and polycarbonatediol compound.

Examples of the polyetherdiol compound include compounds represented byformulae (7), (8), (9), (10) and (11) shown below and a random copolymerof ethylene oxide and propylene oxide having a hydroxy group at theterminal thereof.

In the formulae (7) to (11), R¹⁴ represents a hydrogen atom or a methylgroup. X¹ represents a group shown below. a, b, c, d, e, f and g eachrepresents an integer of 2 or more, and preferably an integer of 2 to100.

Specific examples of the polyetherdiol compound represented by formula(7) or (8) include the following compounds. Specifically, diethyleneglycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol,hexaethylene glycol, heptaethylene glycol, octaethylene glycol,di-1,2-propylene glycol, tri-1,2-propylene glycol, tetra-1,2-propyleneglycol, hexa-1,2-propylene glycol, di-1,3-propylene glycol,tri-1,3-propylene glycol, tetra-1,3-propylene glycol, di-1,3-butyleneglycol, tri-1,3-butylene glycol, hexa-1,3-butylene glycol, polyethyleneglycol having a weight average molecular weight of 1,000, polyethyleneglycol having a weight average molecular weight of 1,500, polyethyleneglycol having a weight average molecular weight of 2,000, polyethyleneglycol having a weight average molecular weight of 3,000, polyethyleneglycol having a weight average molecular weight of 7,500, polypropyleneglycol having a weight average molecular weight of 400, polypropyleneglycol having a weight average molecular weight of 700, polypropyleneglycol having a weight average molecular weight of 1,000, polypropyleneglycol having a weight average molecular weight of 2,000, polypropyleneglycol having a weight average molecular weight of 3,000 andpolypropylene glycol having a weight average molecular weight of 4,000are exemplified.

Specific examples of the polyetherdiol compound represented by formula(9) include the following compounds. Specifically, PTMG650, PTMG1000,PTMG2000 and PTMG3000 (trade name, produced by Sanyo ChemicalIndustries, Ltd.) are exemplified.

Specific examples of the polyetherdiol compound represented by formula(10) include the following compounds. Specifically, Newpol PE-61, NewpolPE-62, Newpol PE-64, Newpol PE-68, Newpol PE-71, Newpol PE-74, NewpolPE-75, Newpol PE-78, Newpol PE-108, Newpol PE-128 and Newpol PE-61(trade name, produced by Sanyo Chemical Industries, Ltd.) areexemplified.

Specific examples of the polyetherdiol compound represented by formula(11) include the following compounds. Specifically, Newpol BPE-20,Newpol BPE-20F, Newpol BPE-2ONK, Newpol BPE-20T, Newpol BPE-20G, NewpolBPE-40, Newpol BPE-60, Newpol BPE-100, Newpol BPE-180, Newpol BPE-2P,Newpol BPE-23P, Newpol BPE-3P and Newpol BPE-5P (trade name, produced bySanyo Chemical Industries, Ltd.).

Specific examples of the random copolymer of ethylene oxide andpropylene oxide having a hydroxy group at the terminal thereof includethe following compounds. Specifically, Newpol 50HB-100, Newpol 50HB-260,Newpol 50HB-400, Newpol 50HB-660, Newpol 50HB-2000 and Newpol 50HB-5100(trade name, produced by Sanyo Chemical Industries, Ltd.).

Examples of the polyesterdiol compound include compounds represented byformulae (12) and (13) shown below.

In formulae (12) and (13), L², L³ and L⁴, which may be the same ordifferent, each represents a divalent aliphatic or aromatic hydrocarbongroup, and L⁵ represents a divalent aliphatic hydrocarbon group.Preferably, L², L³ and L⁴ each represents an alkylene group, analkenylene group, an alkynylene group or an arylene group, and L⁵represents an alkylene group. Also, L², L³, L⁴ and L⁵ each may haveother functional group which does not react with the isocyanate group,for example, an ether group, a carbonyl group, an ester group, a cyanogroup, an olefin group, a urethane group, an amido group, a ureido groupor a halogen atom. n1 and n2 each represents an integer of 2 or more,and preferably an integer of 2 to 100.

Examples of the polycarbonatediol compound include compounds representedby formula (14) shown below.

In formula (14), L⁶, which may be the same or different, each representsa divalent aliphatic or aromatic hydrocarbon group. Preferably, L⁶represents an alkylene group, an alkenylene group, an alkynylene groupor an arylene group. Also, L⁶ may have other functional group which doesnot react with the isocyanate group, for example, an ether group, acarbonyl group, an ester group, a cyano group, an olefin group, aurethane group, an amido group, a ureido group or a halogen atom. n3represents an integer of 2 or more, and preferably an integer of 2 to100.

Specific examples of the diol compound represented by formula (12), (13)or (14) include Compound No. 1 to Compound No. 18 set forth below. Inthe specific examples, n represents an integer of 2 or more.

Also, in the synthesis of the specific polyurethane resin, a diolcompound having a substituent which does not react with the isocyanategroup in addition to the above-described diol compound can be used. Sucha diol compound includes compounds represented by formulae (15) and (16)shown below.HO-L⁷-O—CO-L⁸-CO—O-L⁷-OH   (15)HO-L⁸-CO—O-L⁷-OH   (16)

In formulae (15) and (16), L⁷ and L⁸, which may be the same ordifferent, each represents a divalent aliphatic hydrocarbon group,aromatic hydrocarbon group or heterocyclic group, each of which may havea substituent (for example, an alkyl group, an aralkyl group, an arylgroup, an alkoxy group, an aryloxy group or a halogen atom (e.g., —F,—Cl, —Br or —I)). L⁷ and L⁸ each may have other functional group whichdoes not react with the isocyanate group, for example, a carbonyl group,an ester group, a urethane group, an amido group or a ureido group, ifdesired. Alternatively, L⁷ and L⁸ may be combined with each other toform a ring.

Further, in the synthesis of the specific polyurethane resin, a diolcompound having an acid group, for example, a carboxyl group, a sulfonegroup or a phosphoric group can be used together. Particularly, the diolcompound having a carboxyl group is preferable from the standpoint ofimprovement in film strength and water resistance resulting from ahydrogen bond. Examples of the diol compound having a carboxyl groupinclude compounds represented by formulae (17) to (19) shown below.

In formulae (17) to (19), R¹⁵ represents a hydrogen atom, an alkylgroup, or an aralkyl group, an aryl group, an alkoxy group or an aryloxygroup, each of which may have a substituent (for example, a cyano group,a nitro group, a halogen atom (e.g., —F, —Cl, —Br or —I), —CONH₂,COOR¹⁶, —OR¹⁶, —NHCONHR¹⁶, —NHCOOR⁶, —NHCOR¹⁶ or OCONHR¹⁶ (wherein R¹⁶represents an alkyl group having from 1 to 10 carbon atoms or an aralkylgroup having from 7 to 15 carbon atoms)), and preferably a hydrogenatom, an alkyl group having from 1 to 8 carbon atoms or an aryl grouphaving from 6 to 15 carbon atoms. L⁹, L¹⁰ and L¹¹, which may be the sameor different, each represents a single bond or a divalent aliphatic oraromatic hydrocarbon group which may have a substituent (preferably, forexample, an alkyl group, an aralkyl group, an aryl group, an alkoxygroup or a halogen atom), preferably an alkylene group having from 1 to20 carbon atoms or an arylene group having from 6 to 15 carbon atoms,and more preferably an alkylene group having from 1 to 8 carbon atoms.Also, if desired, L⁹, L¹⁰ and L¹¹ each may contain other functionalgroup which does not react with the isocyanate group, for example, acarbonyl group, an ester group, a urethane group, an amido group, aureido group or an ether group. Further, two or three of R¹⁵, L⁹, L¹⁰and L¹¹ may be combined with each other to form a ring.

Ar represents a trivalent aromatic hydrocarbon group which may havesubstituent, aid preferably an aromatic group having from 6 to 15 carbonatoms.

Specific examples of the diol compound having a carboxy grouprepresented by formula (17), (18) or (19) include the followingcompounds. Specifically, 3,5-dihydroxybenzoic acid,2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(2-hydroxyethyl)propionicacid, 2,2-bis(3-hydroxypropyl)propionic acid, bis(hydroxymethyl)aceticacid, bis(4-hydroxyphenyl)acetic acid, 2,2-bis(hydroxymethyl)butyricacid, 4,4-bis(4-hydroxyphenyl)pentanoic acid, tartaric acid,N,N-dihydroxyethylglycine andN,N-bis(2-hydroxyethyl)-3-carboxypropionamide are exemplified.

Moreover, in the synthesis of the specific polyurethane resin, acompound obtained by ring opening of tetracarboxylic acid dianhydriderepresented by formulae (20) to (22) shown below with a diol compoundcan be used together.

In formulae (20) to (22), L¹² represents a single bond, a divalentaliphatic or aromatic hydrocarbon group which may have a substituent(preferably, for example, an alkyl group, an aralkyl group, an arylgroup, an alkoxy group, a halogen atom, an ester group or an amidogroup), —CO—, —SO—, —SO₂—, —O— or -s-, and preferably a single bond, adivalent aliphatic hydrocarbon group having from 1 to 15 carbon atoms,—CO—, —SO₂—, —O— or -s-. R¹⁷ and R¹⁸, which may be the same ordifferent, each represents a hydrogen atom, an alkyl group, an aralkylgroup, an aryl group, an alkoxy group or a halogen atom, and preferablya hydrogen atom, an alkyl group having from 1 to 8 carbon atoms, an arylgroup having from 6 to 15 carbon atoms, an alkoxy group having from 1 to8 carbon atoms or a halogen atom. Alternatively, two of L¹², R¹⁷ and R¹⁸may be combined with each other to form a ring R¹⁹ and R²⁰, which may bethe same or different, each represents a hydrogen atom, an alkyl group,an aralkyl group, an aryl group or a halogen atom, and preferably ahydrogen atom, an alkyl group having from 1 to 8 carbon atoms or an arylgroup having from 6 to 15 carbon atoms. Alternatively, two of L¹², R¹⁹and R²⁰ may be combined with each other to form a ring. L¹³ and L¹⁴,which may be the same or different, each represents a single bond, adouble bond or a divalent aliphatic hydrocarbon group, and preferably asingle bond, a double bond or a methylene group. A represents amonocyclic or polycyclic aromatic ring, and preferably an aromatic ringhaving from 6 to 18 carbon atoms.

Specific examples of the compound represented by formula (20), (21) or(22) include the following compounds. Specifically, an aromatictetracarboxylic acid dihydride, for example, pyromellitic aciddihydride, 3,3′,4,4′-benzophenonetetracarboxylic acid dihydride,3,3′,4,4′-diphenyltetracarboxylic acid dihydride,2,3,6,7-naphthalenetetracarboxylic acid dihydride,1,4,5,8-naphthalenetetracarboxylic acid dihydride,4,4′-sulfonyldiphthalic acid dihydride,2,2-bis(3,4-dicarboxyphenyl)propane dihydride,bis(3,4-dicarboxyphenyl)ether dihydride,4,4′-[3,3′(alkylphosphoryldiphenylene)-bis(iminocarbonyl)]diphthalicacid dihydride, adduct of hydroquinonediacetate and trimellitic acidanhydride or adduct of diacetyldiamine and trimellitic acid anhydride;an alicyclic tetracarboxylic acid dihydride, for example,5-(2,5-dioxotetrahydrofuryl)-3-methyl-3 -cyclohexene-1,2-dicarboxylicacid dihydride (Epicron B-4400, produced by Dainippon Ink and Chemicals,Inc.), 1,2,3 4-cyclopentanetetracarboxylic acid dihydride,1,2,4,5-cyclohexanetetracarboxylic acid dihydride ortetrahydrofurantetracarboxylic acid dihydride; and an aliphatictetracarboxylic acid dihydride, for example,1,2,3,4-butanetetracarboxylic acid dihydride or1,2,4,5-pentanetetracarboxylic acid dihydride are exemplified.

A method of introducing the compound obtained by ring opening oftetracarboxylic acid dianhydride with a diol compound into thepolyurethane resin includes, for example, the following methods:

a) Method wherein an alcohol-terminated compound obtained byring-opening of the tetracarboxylic acid dianhydride with a diolcompound is reacted with a diisocyanate compound, and

b) Method wherein an alcohol-terminated urethane compound obtained byreacting a diisocyanate compound under an excess diol compound conditionis reacted with the tetracarboxylic acid dianhydride.

Specific examples of the diol compound for use in the ring-openingreaction include the following compounds. Specifically, ethylene glycol,diethylene glycol, triethylene glycol, tetraethylene glycol, propyleneglycol, dipropylene glycol, polyethylene glycol, polypropylene glycol,neopentyl glycol, 1,3-butylene glycol, 1,6-hexanediol,2-butene-1,4-diol, 2,2,4-trimethyl-1,3-pentanediol,1,4-bis-β-hydroxyethoxycyclohexane, cyclohexanedimethanol,tricylodecanedimethanol, hydrogenated bisphenol A, hydrogenatedbisphenol F, an ethylene oxide adduct of bisphenol A, a propylene oxideadduct of bisphenol A, an ethylene oxide adduct of bisphenol F, apropylene oxide adduct of bisphenol F, an ethylene oxide adduct ofhydrogenated bisphenol A, a propylene oxide adduct of hydrogenatedbisphenol A, hydroquinone dihydroxy ethyl ether, p-xylylene glycol,dihydroxyethylsulfone, bis(2-hydroxyethyl)-2,4-tolylenedicarbamate,2,4-tolylene-bis(2-hydroxyethylcarbamide),bis(2-hydroxyethyl)-m-xylylenedicarbamate andbis(2-hydroxyethyl)isophthalate are exemplified.

The specific polyurethane resin according to the invention may includean organic group comprising at least one of an ether bond, an amidobond, a urea bond, an ester bond, a urethane bond, a biuret bond and anarophanato bond, as a functional group, in addition to the urethanebond.

In particular, it is preferred that the specific polyurethane resinfurther has a carbonate site and/or an acetal site in addition to theurethane bond.

In the case wherein the specific polyurethane resin has a carbonatesite, it is believed that carbon dioxide gas resulting from heatdecomposition of the carbonate site generates simultaneously with heatdecomposition of the urethane bond in the main chain and the carbondioxide gas assists heat decomposition of the specific polyurethaneresin and scattering or removing of the heat-decomposed material, and asa result laser decomposition sensitivity is improved and depth of laserengraving increases.

The carbonate site may be present any one of the main chain and sidechain of the polyurethane resin and is preferably present in the mainchain from the stand point of improvement in the laser decompositionsensitivity. More preferably, the carbonate sites are present in mainchain and side chain.

In order to produce the specific polyurethane resin having a carbonatesite, two embodiments can be considered, including an embodiment whereinthe diisocyanate, as a raw material, has the carbonate site and anembodiment wherein the diol, as a raw material, has the carbonate site.Any embodiment may be used according to the invention. The embodimentwherein the diol has the carbonate site is preferable in view of ease ofsynthesis of raw material.

The content of repeating unit including the carbonate site in thespecific polyurethane resin is preferably from 0.1 to 50% by mole, morepreferably from 5 to 50% by mole, particularly preferably from 20 to 50%by mole, based on the total molar amount of raw materials constitutingthe specific polyurethane resin in view of preferably maintaining boththe laser decomposition sensitivity and film-forming property.

Of the specific polyurethane resins according to the invention, thoseincluding a urethane bond wherein both R₁ and R₂ in formula (1) arearomatic groups (both adjacent sides of the urethane bond are aromaticgroups) and having the carbonate site in the main chain are particularlypreferable.

Preferable examples of the raw material for the specific polyurethaneresin having a carbonate site include tie above-described polycarbonatediol compounds.

In the case wherein the specific polyurethane resin has an acetal site,on the other hand, it is believed that since the acetal site decomposessimultaneously with or at lower temperature than heat decomposition ofthe urethane bond in the main chain, the heat decomposition efficiencyof the specific polyurethane resin is totally increased, and as aresult, laser decomposition sensitivity is improved and depth of laserengraving increases.

The acetal site is preferably introduced into the main chain from thestand point of the laser decomposability. In order to produce thespecific polyurethane resin having an acetal site, two embodiments canbe considered, including an embodiment wherein the diisocyanate, as araw material, has the acetal site and an embodiment wherein the dial, asa raw material, has the acetal site. Any embodiment may be usedaccording to the invention. The embodiment wherein the diol has theacetal site is preferable in view of ease of synthesis of raw material.

The content of repeating unit including the acetal site in the specificpolyurethane resin is preferably from 0.1 to 50% by mole, morepreferably from 5 to 50% by mole, particularly preferably from 20 to 50%by mole, based on the total molar amount of raw materials constitutingthe specific polyurethane resin in view of preferably maintaing both thelaser decomposition sensitivity and film-forming property.

Of the specific polyurethane resins, those including a urethane bondwherein both R₁ and R₂ in formula (1) are aromatic groups (both adjacentsides of the urethane bond are aromatic groups) and having the acetalsite in the main chain are particularly preferable.

The acetal site-containing diol compound used for the raw material maybe a chain form or a cyclic form.

Preferable examples of the raw material for the specific polyurethaneresin having an acetal site include acetal diol compounds set forthbelow.

In formulae (A-1) and (A-2), R₁ and R₂, which may be the same ordifferent, each represents a divalent organic group which may have asubstituent (for example, a divalent aliphatic hydrocarbon group,aromatic hydrocarbon group or heterocyclic group which may have, forexample, an alkyl group, an aralkyl group, an aryl group, an alkoxygroup, an aryloxy group or a halogen atom (e.g., —F, —Cl, —Br or —I),and R₃ and R₄, which may be the same or different, each represents ahydrogen atom or a monovalent organic group which may have a substituent(for example, an alkyl group, aralkyl group or aryl group which mayhave, for example, an alkyl group hang from 1 to 10 carbon atoms or anaralkyl group having from 7 to 15 carbon atoms, and each preferablyrepresents a hydrogen atom, an alkyl group having from 1 to 8 carbonatoms or an aryl group having from 6 to 15 carbon atoms.

The acetal diol compound represented by formula (A-2) is preferable fromthe standpoint of the laser decomposability and film-forming property ofthe polyurethane produced by using the diol compound as the rawmaterial.

Specific examples of the acetal diol compound are set forth below, butthe invention should not be construed as being limited thereto.

It is preferred that the specific polyurethane resin for use in theinvention further includes a unit having an ethylenically unsaturatedbond. As the polyurethane resin including a unit having an ethylenicallyunsaturated bond, the resin having at least one functional grouprepresented by formulae (1) to (3) shown below in the side chain thereofis preferable. The functional groups represented by formulae (1) to (3)will be described below.

In formula (1), R¹ to R³ each independently represents a hydrogen atomor a monovalent organic group. R¹ preferably includes, for example, ahydrogen atom or an alkyl group which may have a substituent. Amongthem, a hydrogen atom or a methyl group is preferable because of highradical reactivity. R² and R³ each independently preferably includes,for example, a hydrogen atom, a halogen atom, an amino group, a carboxylgroup, an alkoxycarbonyl group, a sulfo group, a nitro group, a cyanogroup, an alkyl group which may have a substituent, an aryl group whichmay have a substituent, an alkoxy group which may have a substituent anaryloxy group which may have a substituent, an alkylamino group whichmay have a substituent an arylamino group which may have a substituent,an alkylsulfonyl group which may have a substituent and an arylsulfonylgroup which may have a substituent. Among them, a hydrogen atom, acarboxyl group, an alkoxycarbonyl group, an alkyl group which may have asubstituent or an aryl group which may have a substituent is preferablebecause of high radical reactivity.

X represents an oxygen atom, a sulfur atom or —N(R¹²)—, and R¹²represents a hydrogen atom or a monovalent organic group. The monovalentorganic group represented by R¹² includes, for example, an alkyl groupwhich may have a substituent. Among them, a hydrogen atom, a methylgroup, an ethyl group or an isopropyl group is preferable because ofhigh radical reactivity.

Examples of the substituent capable of being introduced include an alkylgroup, an alkenyl group, an alkynyl group, an aryl group, an alkoxygroup, an aryloxy group, a halogen atom, an amino group, an alkylaminogroup, an arylamino group, a carboxyl group, an alkoxycarbonyl group, asulfo group, a nitro group, a cyano group, an amido group, analkylsulfonyl group and an arylsulfonyl group.

In formula (2), R⁴ to R⁸ each independently represents a hydrogen atomor a monovalent organic group. R⁴ to R⁸ each independently preferablyincludes, for example, a hydrogen atom, a halogen atom, an amino group,a dialkylamino group, a carboxyl group, an alkoxycarbonyl group, a sulfogroup, a nitro group, a cyano group, an alkyl group which may have asubstituent, an aryl group which may have a substituent, an alkoxy groupwhich may have a substituent, an aryloxy group which may have asubstituent, an alkylamino group which may have a substituent, anarylamino group which may have a substituent, an alkylsulfonyl groupwhich may have a substituent and an arylsulfonyl group which may have asubstituent. Among them, a hydrogen atom, a carboxyl group, analkoxycarbonyl group, an alkyl group which may have a substituent or anaryl group which may have a substituent is preferable.

Examples of the substituent capable of being introduced include thosedescribed in Formula (1). Y represents an oxygen atom a sulfur atom or—N(R¹²)—, and R¹² has the same meaning as R¹² defined in Formula (1).Preferable examples of R¹² are also same as those described in Formula(1).

In formula (3), R⁹ to R¹¹ each independently represents a hydrogen atomor a monovalent organic group. R⁹ preferably represents a hydrogen atomor an alkyl group which may have a substituent. Among them, a hydrogenatom or a methyl group is preferable because of high radical reactivity.R¹⁰ and R¹¹ each independently preferably increases, for example, ahydrogen atom, a halogen atom, an amino group, a dialkylamino group, acarboxyl group, an alkoxycarbonyl group, a sulfo group, a nitro group, acyano group, an alkyl group which may have a substituent, an aryl groupwhich may have a substituent, an alkoxy group which may have asubstituent, an aryloxy group which may have a substituent, analkylamino group which may have a substituent an arylamino group whichmay have a substituent, an alkylsulfonyl group which may have asubstituent and an arylsulfonyl group which may have a substituent.Among them, a hydrogen atom, a carboxyl group, an alkoxycarbonyl group,an alkyl group which may have a substituent or an aryl group which mayhave a substituent is preferable because of high radical reactivity.

Examples of the substituent capable of being introduced include thosedescribed in Formula (1). Z represents an oxygen atom, a sulfur atom,—N(R¹³)— or a phenylene group which may have a substituent. R¹³preferably includes, for example, an alkyl group which may have asubstituent. Among them, a methyl group, an ethyl group or an isopropylgroup is preferable because of high radical reactivity.

In order to introduce the ethylenically unsaturated bond into the sidechain of the polyurethane resin, a method of using as a raw material forthe production of polyurethane resin, the diol compound having theethylenically unsaturated bond in its side chain is preferable. Specificexamples of the diol compound may include a commercially availablecompound, for example, trimethylolpropane monoalkyl ether and compoundseasily prepared by a reaction between a halogenated diol compound, triolcompound or aminodiol compound and a carboxylic acid, acid chloride,isocyanate, alcohol, amine, thiol or halogenated alkyl compound eachcontaining the ethylenically unsaturated bond. Specific examples of thediol compound are set forth below, but the invention should not beconstrued as being limited thereto.

Also, as a more preferable polyurethane resin according to theinvention, a polyurethane resin obtained by using a diol compoundrepresented by formula (G) shown below, as one of the diol compoundshaving the ethylenically unsaturated bond in the synthesis ofpolyurethane resin is exemplified.

In formula (G), R¹ to R³, each independently represents a hydrogen atomor a monovalent organic group, A represents a divalent organic residue,X represents an oxygen atom, a sulfur atom or —N(R¹²)—, and R²represents a hydrogen atom or a monovalent organic group.

R¹ to R³ and X in formula (G) have the same meaning as R¹ to R³ and Xdefined in formula (1) above, respectively. Preferable examples of R¹ toR³ and X are also same as those described in Formula (1).

By using the polyurethane resin resulting from such a diol compound, itis believed that improvement in the film strength of layer can beachieved by the effect of inhibiting excess molecular motion of thepolymer main chain due to the secondary alcohol having a large sterichindrance.

Specific examples of the diol compound represented by formula (G)preferably used in the synthesis of specific polyurethane resin are setfor the below.

When the polyurethane resin is synthesized under condition of an excessNCO group, specifically, at an NCO/OH ratio of more than 1, the terminalof main chain becomes the NCO group, and by separately adding an alcoholhaving an ethylenically unsaturated bond (for example, 2-hydroxyethyl(meth)acrylate, Blemmer PME200, produced by NOF Corp.) to conductaddition thereto, the ethylenically unsaturated bond can be introducedinto the terminal of main chain. According to the invention, as well asthe side chain, the terminal of main chain may have the ethylenicallyunsaturated bond.

The specific polyurethane resin can be synthesized by heating thediisocyanate compound and diol compound described above in an aproticsolvent in the presence of a known catalyst having an activityresponding to the reactivity of the compounds. A molar ratio (Ma:Mb) ofthe diisocyanate compound to the diol compound used in the synthesis ispreferably from 1:1 to 1.2:1, and by treating, for example, with analcohol or an amine, the product having desired physical properties, forexample, molecular weight or viscosity and containing no residualisocyanate group can be finally synthesized.

The synthesis using a bismuth catalyst is preferable in comparison withat using a tin catalyst conventionally often used from the standpoint ofenvironment and polymerization rate. As the bismuth catalyst, NeostanU-600 (trade name, produced by Nitto Kasei Co., Ltd.) is particularlypreferable.

As for the specific polyurethane resin according to the invention, thathaving an ethylenically unsaturated bond in the polymer terminal and/orpolymer main chain is also preferably used.

A method for introducing the unsaturated group into the polymer terminalincludes the following method. Specifically, a method is exemplifiedwherein in the step of treatment of the residual isocyanate group at thepolymer terminal, for example, with an alcohol or amine in the synthesisof polyurethane resin described above, an alcohol or amine having theunsaturated group is used.

A method for introducing the unsaturated group into the polymer mainchain includes a method of using a diol compound having the unsaturatedgroup in the direction of main chain in the synthesis of polyurethaneresin. Specific examples of the diol compound having the unsaturatedgroup in the direction of main chain include the following compounds.Specifically, cis-2-butene-1,4-diol, trans-2-butene-1,4-diol andpolybutadienediol are exemplified.

The ethylenically unsaturated bond is preferably introduced into thepolymer side chain rather than the polymer terminal because control ofthe introduction amount is easy so that the introduction amount can beincreased and efficiency of crosslinking reaction increases.

The ethylenically unsaturated bond group introduced is preferably amethacryloyl group, acryloyl group or a styryl group, more preferably amethacryloyl group or acryloyl group, in view of crosslinked curedlayer-forming property. From the standpoint of the crosslinked curedlayer-forming property and storage stability of the resin composition, amethacryloyl group is more preferable.

With respect to the amount of ethylenically unsaturated bond introducedinto the specific polyurethane resin according to the invention, theamount of ethylenically unsaturated bond group introduced into the sidechain is preferably 0.3 meq/g or more, more preferably from 0.35 to 1.50meq/g, in terms of equivalent Specifically, the polyurethane resincontaining the methacryloyl group in the side chain in an amount of 0.35to 1.50 meq/g is most preferable.

The molecular weight of the specific polyurethane resin according to theinvention is preferably 10,000 or more, more preferably in a range of40,000 to 200,000, in terms of weight average molecular weight. Inparticular, when the laser-decomposable resin composition according tothe invention is used in an image-recording layer of a pattern-formingmaterial, excellent strength of the image area is obtained in theabove-described range of weight average molecular weight.

Specific examples of the specific polyurethane resin for use in theinvention are set forth below, but the invention should not be construedas being limited thereto. Weight Poly- Average ure- Molec- thane ularResin Diisocyanate Compound Used (% by mole) Diol Compound Used (% bymole) Weight P-1 

 95,000 P-2 

 98,000 P-3 

103,000 P-4 

108,000 P-5 

 99,000 P-6 

 96,000 P-7 

 68,000 P-8 

 96,000 P-9 

100,000 P-10

 69,000 P-11

120,000 P-12

 78,000 P-13

103,000 P-14

 65,000 P-15

 78,000 P-16

 69,000 P-17

 99,000 P-18

 87,000 P-19

 97,000 P-20

103,000 P-21

 60,000 P-22

 70,000 P-23

 50,000 P-24

 75,000 P-25

 80,000 P-26

 50,000 P-27

 60,000 P-28

 59,000 P-29

 63,000 P-30

 32,000 P-31

 21,000 P-32

 29,000 P-33

 41,000 P-34

 67,000 P-35

 69,000 P-36

 68,000 P-37

 48,000 P-38

 50,000 P-39

 47,000

The specific polyurethane resin according to the invention has a featurethat it is heat-decomposed at relatively low temperature (not higherthan 250° C.) in comparison with a binder polymer of a conventionallaser decomposable resin composition (most commercially availableconventional resins are heat-decomposed at high temperature of 300 to400° C.). Therefore, the laser-decomposable resin composition comprisingthe specific polyurethane resin can be decomposed in high sensitivity.Also, even in a system where the specific polyurethane resin is usedtogether with a binder polymer particularly, in the state of phaseseparation), due to heat generation upon laser irradiation, the specificpolyurethane resin is first decomposed and gas (for example, nitrogengas) generated at the vaporization accompanied with the heatdecomposition of the specific polyurethane resin assists and acceleratesvaporization of the coexisting binder polymer. Accordingly, it isbelieved that the laser-decomposable resin composition containing thespecific polyurethane resin and the binder polymer is improved in thelaser decomposability to achieve the high sensitivity in comparison witha case wherein the specific polyurethane resin is not contained.

It is also possible to use a polyurethane resin other than the specificpolyurethane resin is used together with the specific polyurethane resinaccording to the invention insofar as the effects of the invention arenot impaired.

<Binder Polymer>

The laser-decomposable resin composition according to the invention maycontain a binder polymer. It is useful for the binder polymer to formthe state of phase separation when it is used together with the specificpolyurethane resin according to the invention. The binder polymerincluded in the laser-decomposable resin composition according to theinvention is preferably a binder polymer having a carbon-carbonunsaturated bond in any one of its main chain and side chain. A polymercontaining any one of an olefin bond (carbon-carbon double bond) and acarbon-carbon triple bond in its main chain is more preferable in viewof ease of formation of the state of phase separation and highmechanical strength of the layer formed, and a polymer containing theolefin bond in its main chain is particularly preferable.

The polymer containing any one of an olefin bond and a carbon-carbontriple bond in its main chain includes, for example, SB(polystyrene-polybutadiene), SBS(polystyrene-polybutadiene-polystyrene), SIS(polystyrene-polyisoprene-polystyrene) or SEBS(polystyrene-polyethylene/polybutylene-polystyrene).

The confirmation of the phase separation can be performed by observationwith SEM (scanning electron microscope). In particular, the polymercontaining any one of an olefin bond and a carbon-carbon triple bond inits main chain is apt to undergo the phase separation and has a featurethat it is stained upon contact with an osmium compound. On the otherhand, since the specific polyurethane resin according to the inventionis not stained with the osmium compound, it has an advantage in that theconfirmation of the phase separation becomes easy by conducting thetreatment of a sample of the phase separation with the osmium compoundprior to the observation with SEM.

The number average molecular weight of the binder polymer is preferablyin a range of 1,000 to 1,000,000, more preferably in a range of 5,000 to500,000. When the number average molecular weight thereof is in therange of 1,000 to 1,000,000, the mechanical strength of the layer formedcan be ensured. The term “number average molecular weigh” as used hereinmeans a molecular weight obtained by measuring using gel permeationchromatography (GPC) and calculating in terms of standard polystyrene ofa known molecular weight.

In the case wherein the laser-decomposable resin composition accordingto the invention contains the binder polymer, the amount of the binderpolymer added is ordinarily from 1 to 99% by weight preferably from 5 to80% by weight based on the total solid content of the resin composition.

Moreover, according to the invention, the binder polymer described abovemay be used together with a conventional resin described below. Theamount of the resin used together is ordinarily from 1 to 90% by weight,preferably from 5 to 80% by weight, based on the binder polymerdescribed above.

The resin used together may be an elastomer or a non-elastomer.

The number average molecular weight of the resin used together ispreferably in a range of 1,000 to 1,000,000, more preferably in a rangeof 5,000 to 500,000. when the number average molecular weight thereof isin the range of 1,000 to 1,000,000, the mechanical strength of the layerformed can be ensured. The term “number average molecular weigh” as usedherein means a molecular weight obtained by measuring using gelpermeation chromatography (GPC) and calculating in terms of standardpolystyrene of a known molecular weight.

As the resin used together, a resin easily liquefiable or a resin easilydecomposable is preferable. The resin easily decomposable preferablycontains in the molecular chain as a monomer unit easily decomposable,for example, a monomer unit derived from styrene, α-methylstyrene,α-methoxystyrene, an acryl ester, a methacryl ester, an ester compound,an ether compound, a nitro compound, a carbonate compound, a carbamoylcompound, a hemiacetal ester compound, an oxyethylene compound or analiphatic cyclic compound. In particular, a polyether, for example,polyethylene glycol, polypropylene glycol or polytetraethylene glycol,an aliphatic polycarbonate, an aliphatic polycarbamate, polymethylmethacrylate, polystyrene, nitrocellulose, polyoxyethylene,polynorbornene, hydrogenated polycyclohexadiene or a polymer having amolecular structure of many branched structures, for example, adendrimer is the representative example of the resin easilydecomposable. Also, a polymer containing a lot of oxygen atoms in themolecular chain is preferable from the standpoint of thedecomposability. Among them, the compound having a carbonate group, acarbamate group or a methacryl group in the polymer main chain ispreferable in view of the high heat decomposability. For instance, apolyester or polyurethane synthesized using as the raw material,(poly)carbonatediol or (poly)carbonate dicarboxylic acid or a polyamidesynthesized using as the raw material, (poly)carbonate diamine isillustrated as a preferable example of the polymer of good heatdecomposability. The polymer may contain a polymerizable unsaturatedgroup in the main chain or side chain thereof. In particular, when thepolymer has a reactive functional group, for example, a hydroxy group,an amino group or a carboxyl group at the terminal, it is easy tointroduce the polymerizable unsaturated group.

The thermoplastic elastomer is not particularly restricted and includes,for example, a urethane-series thermoplastic elastomer, an ester-seriesthermoplastic elastomer, an amide-series thermoplastic elastomer or asilicone-series thermoplastic elastomer. In order to more increase theheat decomposability, a polymer wherein an easily decomposablefunctional group, for example, a carbamoyl group or a carbonate group isintroduced into its main chain can be used. Also, it may be used as amixture with a polymer of higher heat decomposability. Since thethermoplastic elastomer is fluidized by heating, it is possible to mixwith the complex for use in the invention. The term “thermoplasticelastomer” as used herein means a material which exhibits rubberelasticity at ambient temperature and is fluidized by heating to undergofabrication as an ordinary thermoplastic plastic. With respect to themolecular structure, the thermoplastic elastomer comprises a softsegment like a polyether or a rubber molecule and a hard segment whichprevents plastic deformation around ambient temperature as vulcanizedrubber. As the hard segment, various types, for example, a frozen phase,a crystalline phase, a hydrogen bond or an ionic crosslinkage arepresent.

The kind of thermoplastic elastomer can be selected depending on the useof the resin composition. For instance, in the field requiring solventresistance, a urethane-series, ester-series, amide-series orfluorine-series thermoplastic elastomer is preferable and in the fieldrequiring heat resistance, a urethane-series, olefin-series,ester-series or fluorine-series thermoplastic elastomer is preferable.Further, the hardness can be widely changed depending on the kind ofthermoplastic elastomer.

The non-elastomeric thermoplastic resin is not particularly restrictedand includes, for example, a polyester resin, an unsaturated polyesterresin, a polyamide resin, a polyamideimide resin, a polyurethane resin,an unsaturated polyurethane resin a polysulfone resin, apolyethersulfone resin, a polyimide resin, a polycarbonate resin and afull aromatic polyester resin.

A hydrophilic polymer may be used as the resin used together. Thehydrophilic polymer includes, for example, a hydrophilic polymercontaining hydroxyethylene as a constituting unit. Specifically,polyvinyl alcohol, a vinyl alcohol/vinyl acetate copolymer (partiallysaponified polyvinyl alcohol) and a modified product thereof areexemplified. The hydrophilic polymers may be used individually or incombination of two or more thereof. Examples of the modified productinclude a polymer wherein at least a part of hydroxy groups are modifiedto carboxyl groups, a polymer wherein at least a part of hydroxy groupsare modified to (meth)acryloyl groups, a polymer wherein at least a partof hydroxy groups are modified to amino groups, and a polymer havingethylene glycol, propylene glycol or a dimer thereof introduced into itsside chain.

The polymer wherein at least a part of hydroxy groups are modified tocarboxyl groups can be obtained by esterification of polyvinyl alcoholor partially saponified polyvinyl alcohol with a polyfunctionalcarboxylic acid, for example, succinic acid, maleic acid or adipic acid.

The polymer wherein at least a part of hydroxy groups are modified to(meth)acryloyl groups can be obtained by addition of a glycidylgroup-containing ethylenically unsaturated monomer to theabove-described carboxyl group-modified polymer or by esterification ofpolyvinyl alcohol or partially saponified polyvinyl alcohol with(meth)acrylic acid.

The polymer wherein at least a part of hydroxy groups are modified toamino groups can be obtained by esterification of polyvinyl alcohol orpartially saponified polyvinyl alcohol with a carboxylic acid containingan amino group, for example, carbamic acid.

The polymer having ethylene glycol, propylene glycol or a dimer thereofintroduced into its side chain can be obtained by heating polyvinylalcohol or partially saponified polyvinyl alcohol together with a glycolin the presence of a sulfuric acid catalyst and removing water as abyproduct from the reaction system.

Of the hydrophilic polymers, the polymer wherein at least a part ofhydroxy groups are modified to (meth)acryloyl groups is particularlypreferably used. This is because by the direct introduction of anunreacted crosslinkable functional group to a polymer component,strength of the layer formed can be increased so that both flexibilityand strength of the layer formed can be achieved.

The weight average molecular weight (measured by GPC and calculated interms of polystyrene) of the hydrophilic polymer is preferably from10,000 to 500,000. When the weight average molecular weight is 10,000 ormore, the polymer is excellent the configuration retention property as aresin alone. When the weight average molecular weight is 500,000 orless, the polymer is easily soluble in a solvent, for example, water andadvantageous to the preparation of a crosslinkable resin composition.

Further, the resin used together may be a solvent-soluble resin.Specific examples thereof include a polysulfone resin, apolyethersulfone resin, an epoxy resin, an alkyd resin, a polyolefinresin and a polyester resin.

The resin used together does not ordinarily have a polymerizableunsaturated group having a high reactivity. However, it may have thepolymerizable unsaturated group having a high reactivity at the terminalof the molecular chain or in the side chain. When a polymer having thepolymerizable unsaturated group having a high reactivity, for example, amethacryloyl group is used, a layer having the extremely high mechanicalstrength can be prepared. In particular, as for the polyurethane-seriesor polyester-series thermoplastic elastomer, the polymerizableunsaturated group having a high reactivity can be introduced into themolecule thereof with comparative ease. The terminology “be introducedinto the molecule” as used herein means and includes cases wherein thepolymerizable unsaturated group is directly bonded at both terminals orone terminal of the polymer main chain, at a terminal of the polymerside chain, or in the polymer main chain or side chain. Specifically,for instance, the resin having the polymerizable unsaturated groupdirectly introduced at the terminal of molecule may be used.Alternatively, other method, for example, a method is preferablyemployed in which a compound having a molecular weight of about severalthousands and including plural reactive groups, for example, a hydroxygroup, an amino group, an epoxy group, a carboxyl group, an acidanhydride group, a ketone group, a hydrazine residue, an isocyanategroup, an isothiocyanate group, a cyclic carbonate group or an estergroup is reacted with a bonding agent (for example, a polyisocyanategroup reacting with a hydroxy group or ado group) having a group capableof connecting with the reactive group of the above compound to conductthe adjustment of molecular weight and conversion to a terminal bondinggroup and then the resulting compound is reacted with an organiccompound having a group capable of reacting with the terminal bondinggroup and a polymerizable unsaturated group to introduce thepolymerizable unsaturated group into the terminal.

From the standpoint of achieving more preferable laser decompositionsensitivity, the system of using the specific polyurethane resin aloneis preferable in comparison with the system wherein the specificpolyurethane resin is used together with the binder polymer.

The laser-decomposable resin composition according to the invention mayfurther contain a polymerizable compound (monomer), an initiator andother components, if desired. The polymerizable compound (monomer),initiator and other components will be described hereinafter.

Polymerizable Compound (Monomer)

The polymerizable compound (monomer) is described in greater detailbelow taking a case wherein an addition polymerizable compound is usedas an example.

<Addition Polymerizable Compound>

The addition-polymerizable compound having at least one ethylenicallyunsaturated double bond which is the polymerizable compound preferablyused in the invention is selected from compounds having at least one,preferably two or more, terminal ethylenically unsaturated double bonds.Such compounds are widely known in the field of art and they can be usedin the invention without any particular limitation. The compound has achemical form, for example, a monomer, a prepolymer, specifically, adimer, a trimer or an oligomer, or a copolymer thereof, or a mixturethereof. Examples of the monomer include unsaturated carboxylic acids(for example, acrylic acid, methacrylic acid, itaconic acid, crotonicacid, isocrotonic acid or maleic acid) and esters or amides thereof.Preferably, esters of an unsaturated carboxylic acid with an aliphaticpolyhydric alcohol compound and amides of an unsaturated carboxylic acidwith an aliphatic polyvalent amine compound are used. An additionreaction product of an unsaturated carboxylic acid ester or amide havinga nucleophilic substituent, for example, a hydroxy group, an amino groupor a mercapto group, with a monofunctional or polyfunctional isocyanateor epoxy, or a dehydration condensation reaction product of theunsaturated carboxylic acid ester or amide with a monofunctional orpolyfunctional carboxylic acid is also preferably used. Furthermore, anaddition reaction product of an unsaturated carboxylic acid ester oramide having an electrophilic substituent, for example, an isocyanatogroup or an epoxy group with a monofunctional or polyfunctional alcohol,amine or thiol, or a substitution reaction product of an unsaturatedcarboxylic acid ester or amide having a releasable substituent, forexample, a halogen atom or a tosyloxy group with a monofunctional orpolyfunctional alcohol, amine or thiol is also preferably used. Inaddition, compounds in which the unsaturated carboxylic acid describedabove is replaced by an unsaturated phosphonic acid, styrene, vinylether or the like can also be used.

Specific examples of the monomer, which is an ester of an aliphaticpolyhydric alcohol compound with an saturated carboxylic acid, includeacrylic acid esters, for example, ethylene glycol diacrylate,triethylene glycol diacrylate, 1,3-butanediol diacrylate, tetramethyleneglycol diacrylate, propylene glycol diacrylate, neopentyl glycoldiacrylate, trimethylolpropane triacrylate, trimethylolpropanetri(acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanedioldiacrylate, 1,4-cyclohexanediol diacrylate, tetraethylene glycoldiacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate,pentaerythritol tetraacrylate, dipentaerythritol diacrylate,dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitoltetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate,tri(acryloyloxyethyl) isocyanurate or polyester acrylate oligomer;methacrylic acid esters, for example, tetramethylene glycoldimethacrylate, triethylene glycol dimethacrylate, neopentyl glycoldimethacrylate, trimethylolpropane trimethacrylate, trimethylolethanetrimethacrylate, ethylene glycol dimethacrylate, 1,3-butanedioldimethacrylate, hexanediol dimethacrylate, pentaerythritoldimethacrylate, pentaerythritol trimethacrylate, pentaerythritoltetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritolhexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate,bis[p-(3-methacryloxy-2-hydroxypropoxy)phenyl]dimethylmethane orbis[p-(methacryloxyethoxy)phenyl]dimethylmethane;

itaconic acid esters, for example, ethylene glycol diitaconate,propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanedioldiitaconate, tetramethylene glycol diitaconate, pentaerythritoldiitaconate or sorbitol tetraitaconate;

crotonic acid esters, for example, ethylene glycol dicrotonate,tetramethylene glycol dicrotonate, pentaerythritol dicrotonate orsorbitol tetracrotonate;

isocrotonic acid esters, for example, ethylene glycol diisocrotonate,pentaerythritol diisocrotonate or sorbitol tetraisocrotonate; and

maleic acid esters, for example, ethylene glycol dimaleate, triethyleneglycol dimaleate, pentaerythritol dimaleate and sorbitol tetramaleate.

Other examples of the ester, which can be preferably used, includealiphatic alcohol esters described in JP-B-46-27926 (the term “JP-B” asused herein means an “examined Japanese patent publication”),JP-B-51-47334 and JP-A-57-196231, esters having an aromatic skeletondescribed in JP-A-59-5240, JP-A-59-5241 and JP-A-2-226149, and esterscontaining an amino group described in JP-A-1-165613.

The above-described ester monomers can also be used as a mixture.

Specific examples of the monomer, which is an amide of an aliphaticpolyvalent amine compound with an unsaturated carboxylic acid, includemethylene bisacrylamide, methylene bismethacrylamide, 1,6-hexamethylenebisacrylamide, 1,6-hexamethylene bismethacrylamide, diethylenetraminetrisacrylamide, xylylene bisacrylamide and xylylene bismethacrylamide.

Other preferable examples of tie amide monomer include amides having acyclohexylene structure described in JP-B-54-21726.

Urethane type addition polymerizable compounds produced using anaddition reaction between an isocyanate and a hydroxy group are alsopreferably used, and specific examples thereof include vinylurethanecompounds having two or more polymerizable vinyl groups per moleculeobtained by adding a vinyl monomer containing a hydroxy grouprepresented by formula (V) show below to a polyisocyanate compoundhaving two or more isocyanate groups per molecule, described inJP-B-48-41708.CH₂═C(R)COOCH₂CH(R′)OH   (V)wherein R and R′ each independently represents H or CH₃.

Also, urethane acrylates described in JP-A-51-37193, JP-B-2-32293 andJP-B-2-16765, and urethane compounds having an ethylene oxide skeletondescribed in JP-B-58-49860, JP-B-56-17654, JP-B-62-39417 andJP-B-62-39418 are preferably used.

The urethane type addition polymerizable compound is extremelypreferable because it has good compatibility with the specificpolyurethane resin according to the invention and high engravingsensitivity. Among them, PLEX 6661-0 (produced by Degussa GmbH) isparticularly preferable because it rapidly undergoes heat decomposition(decrease of weight upon the heat decomposition) at approximately 250°C. not only to provide the high engraving sensitivity but also toexhibit high resolution due to shape edge shape of the engravingportion.

Furthermore, the resin composition capable of being cured at short timescan be obtained by using an addition polymerizable compound having anamino structure or a sulfide structure in its molecule described inJP-A-63-277653, JP-A-63-260909 and JP-A-1-105238.

Other examples include polyfunctional acrylates and methacrylates, forexample, polyester acrylates and epoxy acrylates obtained by reacting anepoxy resin with acrylic acid or methacrylic acid described inJP-A-48-64183, JP-B-49-43191 and JP-B-52-30490. Specific unsaturatedcompounds described in JP-B46-43946, JP-B-1-40337 and JP-B-1-40336, andvinylphosphonic acid series compounds described in JP-A-2-25493 can alsobe exemplified. In some cases, structure containing a perfluoroalkylgroup described in JP-A-61-22048 can be preferably used. Moreover,photocurable monomers or oligomers described in Nippon SecchakuKyokaishi (Journal of Japan Adhesion Society), Vol. 20, No. 7, pages 300to 308 (1984) can also be used.

In view of the photo-speed, a structure having a large content ofunsaturated groups per molecule is preferred and in many cases, adifunctional or more functional compound is preferred. In order toincrease the strength of image area that is, cured layer, atrifunctional or more functional compound is preferred. A combinationuse of compounds different in the functional number or in the kind ofpolymerizable group (for example, an acrylic acid ester, a methacrylicacid ester, a styrene compound or a vinyl ether compound) is aneffective method for controlling both the sensitivity and the strength.The polymerizable compound is preferably used in an amount from 5 to 80%by weight, more preferably from 25 to 75% by weight, based on thenonvolatile component of the resin composition. The polymerizablecompounds may be used individually or in combination of two or morethereof. By using the polymerizable compound, the physical properties oflayer, for example, brittleness or flexibility can be adjusted.

Before and/or after the laser decomposition, the laser-decomposableresin composition containing the polymerizable compound can bepolymerized and cured with energy, for example, light or heat.

Preferable specific examples of the polymerizable compound used togetherwith the specific polyurethane resin in the laser-decomposable resincomposition according to the invention are set forth below.

<Initiator>

As the initiator, initiators known to those skilled in the art can beused without limitation. Specifically, many compounds described inliterature, for example, Bruce M. Monroe et al., Chemical Review, 93,435 (1993), R. S. Davidson, Journal of Photochemistry and Biology A:Chemistry, 73, 81 (1993), J. P. Faussier, PhotoinitiatedPolymerization-Theory and Applications: Rapra Review, Vol. 9, ReportRapra Technology (1998) or M. Tsunooka et al., Prog. Polym. Sci., 21, 1(1996) can he used. Further, a group of compounds undergoing oxidativeor reductive bond cleavage as described, for example, in F. D. Saeva,Topics in Current Chemistry, 156, 59 (1990), G. G. Maslak, Topics inCurrent Chemist, 168, 1 (1993), H. B. Shuster et al., JACS, 112, 6329(1990) and I. D. F. Eaton et al., JACS, 102, 3298 (1980) are known.

With respect to specific examples of preferable initiator, a radicalinitiator which is a compound that generates a radical upon light energyand/or heat energy and initiates or promotes a polymerization reactionof the above-described polymerizable compound is described in greaterdetail below, but the invention should not be construed as being limitedthereto.

As the radical initiator preferably used in the invention, (a) anaromatic ketone, t) an onium salt compound, (c) an organic peroxide, (d)a thio compound, (e) a hexaarylbiimidazole compound, (f) a ketoximeester compound, (g) a borate compound, (h) an azinium compound, (i) ametallocene compound, (j) an active ester compound, (k) a compoundhaving a carbon-halogen bond and (l) an azo series compound. Specificexamples of the compounds of (a) to (l) are set forth below, but theinvention should not be construed as being limited thereto.

(a) Aromatic Ketone

The aromatic ketone (a) preferably used as the radical initiator in theinvention includes compounds having a benzophenone skeleton or athioxantone skeleton described in J. P, Fouassier and J. F. Rabek,Radiation Curing in Polymer Science and Technology pages 77 to 117(1993). For example, the following compounds are recited.

Among them, particularly preferable examples of the aromatic ketone (a)include the following compound:

(b) Onium Salt Compound

The onium salt compound (b) preferably used as the radical initiator inthe invention includes compounds represented by the following formulae(1) to (3):

In formula (1), Ar¹ and Ar² each independently represent an aryl grouphaving not more than 20 carbon atoms, which may have a substituent.(Z²)⁻ represents a counter ion selected from the group consisting of ahalogen ion, a perchlorate ion, a carboxylate ion, tetrafluoroborateion, a hexafluorophosphate ion and a sulfonate ion and is preferably aperchlorate ion, a hexafluorophosphate ion and an arylsulfonate ion.

In formula (2), A³ represents an aryl group having not more than 20carbon atoms, which may have a substituent. (Z³)⁻ represents a counterion having the same meaning as defined for (Z²)⁻.

In formula (3), R²³, R²⁴ and R²⁵, which may be the same or different,each represent a hydrocarbon group having not more than 20 carbon atoms,which may have a substituent. (Z⁴)⁻ represents a counter ion having thesame meaning as defined for (Z²)⁻.

Specific examples of the onium salt preferably used in the inventioninclude those described in Paragraph Nos. [0030] to [0033] ofJP-A-2001-133969 and Paragraph Nos. [0015] to [0046] ofJP-A-2001-343742, and specific aromatic sulfonium salt compoundsdescribed in JP-A-2002-148790, JP-A-2001-343742, JP-A-2002-6482,JP-A-2002-116593 and JP-A-2004-102031 both of which the applicant hasbeen previously proposed.

(c) Organic Peroxide

The organic peroxide (c) preferably used as the radical initiator in theinvention includes almost all organic compounds having at least oneoxygen-oxygen bond in the molecules thereof. Specific examples of theorganic peroxide include methyl ethyl ketone peroxide, cyclohexanoneperoxide, 3,3,5-trimethylcyclohexane peroxide, methylcyclohexanoneperoxide, acetylacetone peroxide,1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane,1,1-bis(tert-butylperoxy)cyclohexane, 2,2-bis(tert-butylperoxy)butane,tert-butylhydroperoxide, cumene hydroperoxide, diisopropylbenzenehydroperoxide, paramethane hydroperoxide,2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutylhydroperoxide, di-tert-butyl peroxide, tert-butyl cumyl peroxide,dicumyl peroxide, bis(tert-butylperoxyisopropyl)benzene,2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-xanoyl peroxide,succinic peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide,methatoluoyl peroxide, diisopropylperoxy dicarbonate,di-2-ethylhexylperoxy dicarbonate, di-2-ethoxyethylperoxy dicarbonate,dimethoxyisopropylperoxy dicarbonate, di(3-methyl-3-methoxybutyl)peroxydicarbonate, tert-butylperoxy acetate, tert-butylperoxy pivalate,tert-butylperoxy neodecanoate, tert-butylperoxy octanoate,tert-butylperoxy 3,5,5-trimethylhexanoate, tert-butylperoxy laurate,tertiary carbonate,3,3′,4,4′-tetra(tert-butylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(tert-amylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(tert-hexylperoxycarbonyl)benzophenone,3,3′,4,4-tetra(tert-octylperoxycarbonyl)benzophenone, 3,3′,4,4′-tetra(cumylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(p-isopropylcumylperoxycarbonyl)benzophenone, carbonyldi(tert-butylperoxydihydrogen diphthalate) and carbonyldi(tert-hexylperoxydihydrogen diphthalate).

Among them, peroxy ester compounds, for example,

-   3,3′,4,4′-tetra(tert-butylperoxycarbonyl)benzophenone,-   3,3′,4,4′-tetra(tert-amylperoxycarbonyl)benzophenone,-   3,3′,4,4′-tetra(tert-hexylperoxycarbonyl)benzophenone,-   3,3′,4,4′-tetra(tert-octylperoxycarbonyl)benzophenone,-   3,3′,4,4′-tetra(cumylperoxycarbonyl)benzophenone,-   3,3′,4,4′-tetra(p-isopropylcumylperoxycarbonyl)benzophenone and    d-tert-butyldiperoxy isophthalate are preferred.    (d) Thio Compound

The thio compound (d) preferably used as the radical initiator in theinvention includes compounds having the structure represented by thefollowing formula (4):

In formula (4), R²⁶ represents an alkyl group, an aryl group or asubstituted aryl group. R²⁷ represents a hydrogen atom or an alkylgroup. Alternatively, R²⁶ and R²⁷ combine with each other and togetherrepresent a non-metallic atomic group necessary for forming a5-membered, 6-membered or 7-membered ring, which may contain a heteroatom selected from an oxygen atom, a sulfur atom and a nitrogen atom.

Specific examples of the thio compound represented by formula (4)include the following compounds. No. R²⁶ R²⁷ 1 —H —H 2 —H —CH₃ 3 —CH₃ —H4 —CH₃ —CH₃ 5 —C₆H₅ —C₂H₅ 6 —C₆H₅ —C₄H₉ 7 —C₆H₄Cl —CH₃ 8 —C₆H₄Cl —C₄H₉ 9—C₆H₄—CH₃ —C₄H₉ 10 —C₆H₄—OCH₃ —CH₃ 11 —C₆H₄—OCH₃ —C₂H₅ 12 —C₆H₄—OC₂H₅—CH₃ 13 —C₆H₄—OC₂H₅ —C₂H₅ 14 —C₆H₄—OCH₃ —C₄H₉ 15 —(CH₂)₂— 16 —(CH₂)₂—S—17 —CH(CH₃)—CH₂—S— 18 —CH₂—CH(CH₃)—S— 19 —C(CH₃)₂—CH₂—S— 20—CH₂—C(CH₃)₂—S— 21 —(CH₂)₂—O— 22 —CH(CH₃)—CH₂—O— 23 —C(CH₃)₂—CH₂—O— 24—CH═CH—N(CH₃)— 25 —(CH₂)₃—S— 26 —(CH₂)₂—CH(CH₃)—S— 27 —(CH₂)₃—O— 28—(CH₂)₅— 29 —C₆H₄—O— 30 —N═C(SCH₃)—S— 31 —C₆H₄—NH— 32

(e) Hexaarylbiimidazole Compound

The hexaarylbiimidazole compound (e) preferably used as the radicalinitiator in the invention includes lophine dimers described inJP-B-45-37377 and JP-B-44-86516, specifically, for example,2,2′-bis(o-chlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o-bromophenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o,p-dichlorophenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o-chlorophenyl)-4,4′,5,5′-tetra(m-methoxyphenyl)biimidazole,2,2′-bis(o,o′-dichlorophenyl)-4,4′,5 5′-tetraphenylbiimidazole,2,2′-bis(o-nitrophenyl)-4,4′,5,5′-tetraphenylbiimidazole,2,2′-bis(o-methylphenyl)-4,4′,5,5′-tetraphenylbiimidazole and2,2′-bis(o-trifluoromethylphenyl)-4,4′,5,5′-tetraphenylbiimidazole.

(f) Ketoxime Ester Compound

The ketoxime ester compound (f) preferably used as the radical initiatorin the invention includes, for example, 3-benzoyloxyiminobutan-2-one,3-acetoxyiminobutan-2-one, 3-propyonyloxyiminobutan-2-one,2-acetoxyiminopentan-3-one, 2-acetoxyimino-1-phenylpropan-1-one,2-benzoyloxyimino-1-phenylpropan-1-one,3-p-toluenesulfonyloxyiminobutan-2-one and2-ethoxycarbonyloxyimino-1-phenylpropan-1-one.

(g) Borate Compound

The borate compound (g) preferably used as the radical initiator in theinvention includes compounds represented by the following formula (5):

In formula (5), R²⁸, R²⁹, R³⁰ and R³¹, which may be the same ordifferent, each represents a substituted or unsubstituted alkyl group, asubstituted or unsubstituted aryl group, a substituted or unsubstitutedalkenyl group, a substituted or unsubstituted alkynyl group or asubstituted or unsubstituted heterocyclic group, or at least two of R²⁸,R²⁹, R³⁰ and R³¹ may be combined with each other to form a cyclicstructure, provided that at least one of R²⁸, R²⁹, R³⁰ and R³¹represents a substituted or unsubstituted alkyl group. (Z⁵)⁺ representsan alkali metal cation or a quaternary ammonium cation.

Specific examples of the compound represented by formula (5) includecompounds described in U.S. Pat. Nos. 3,567,453 and 4,343,891, EuropeanPatents 109,772 and 109,773, and the following compounds:

(h) Azinium Compound

The azinium compound (h) preferably used as the radical initiator in theinvention includes compounds having an N—O bond described inJP-A-63-138345, JP-A-63-142345, JP-A-63-142346, JP-A-63-143537 andJP-B-46-42363.

(i) Metallocene Compound

The metallocene compound (i) preferably used as the radical initiator inthe invention includes titanocene compounds described in JP-A-59-152396,JP-A-61-151197, JP-A-63-41484, JP-A-2-249 and JP-A-2-4705, andiron-arene complexes described in JP-A-1-304453 and JP-A-1-152109.

Specific examples of the titanocene compound include

-   dicyclopentadienyl-Ti-dichloride, dicyclopentadienyl-Ti-biphenyl,-   dicyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl,-   dicyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl,-   dicyclopentadienyl-Ti-bis-2,4,6-difluorophen-1-yl,-   dicyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl,-   dicyclopentadienyl-Ti-bis-2,4-difluorophen-1-yl,-   dimethylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl,-   dimethylcyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl,-   dimethylcyclopentadienyl-Ti-bis-2,4-difluorophen-1-yl,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(pyr-1-yl)phenyl]titanium,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(methylsufonamido)phenyl]titanium,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(N-butylpivaloylamino)phenyl]titanium,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(N-butyl-(4-chlorobenzoyl)amino)phenyl]titanium,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(N-benzyl-2,2-dimethylpentanoylamino)phenyl]titanium,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(N-(2-ethylhexyl)-4-tolylsulfonylamino)phenyl]titanium,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(N-(3-oxaheptyl)benzoylamino)phenyl]titanium,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(N-(3,6-dioxadecyl)benzoylamino)phenyl]titanium,-   bis(cylopentadienyl)bis[2,6-difluoro-3-trifluoromethylsulfonylamino)phenyl]titanium,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(trifluoroaceylamino)phenyl]titanium,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(2-chlorobenzoylamino)phenyl]titanium,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(4-chlorobenzoylamino)phenyl]titanium,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(N-(3,6-dioxadecyl)-2,2-dimethylpentanoylamino)phenyl]titanium,-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(N-(3,7-dimethyl-7-methoxyoctyl)benzoylamino)phenyl]titanium    and-   bis(cyclopentadienyl)bis[2,6-difluoro-3-(N-cyclohexylbenzoylamino)phenyl]titanium.    (j) Active Ester Compound

The active ester compound (j) preferably used as the radical initiatorin the invention includes imidosulfonate compounds described inJP-B-62-6223, and active sulfonates described in JP-B-63-14340 andJP-A-59-174831.

(k) Compound Having a Carbon-Halogen Bond

-   The compound having a carbon-halogen bond (k) preferably used as the    radical initiator in the invention includes the compounds    represented by the following formulae (6) to (12):

In formula (6), X² represents a halogen atom, Y¹ represents —C(X²)₃,—NH₂, —NHR³⁸, —N(R³⁸)₂ or —OR³⁸, R³⁸ represents an alkyl group, asubstituted alkyl group, an aryl group or a substituted aryl group, andR³⁷ represents —C(X²)₃, an alkyl group, a substituted alkyl group, anaryl group, a substituted aryl group or a substituted alkenyl group.

In formula (7), R³⁹ represents an alkyl group, a substituted alkylgroup, an alkenyl group, a substituted alkenyl group, an aryl group, asubstituted aryl group, a halogen atom, an alkoxy group, a substitutedalkoxy group, a nitro group or a cyano group, X³ represents a halogenatom, and n represents an integer of 1 to 3.

In formula (8), R⁴⁰ represents an aryl group or a substituted arylgroup, R⁴¹ represents a group shown below or a halogen atom, Z⁶represents —C(′O)—, —C(═S)— or —SO₂—, X³ represents a halogen atom, andm represents 1 or 2.

wherein, R⁴² and R⁴³ each represents an alkyl group, a substituted alkylgroup, an alkenyl group, a substituted alkenyl group, an aryl group or asubstituted aryl group, and R⁴⁴ has the same meaning as defined for R³⁸in formula (6).

In formula (9), R⁴⁵ represents an aryl group which may be substituted ora heterocyclic group which may be substituted, R⁴⁶ represents atrihaloalkyl group or trihaloalkenyl group each having from 1 to 3carbon atoms, and p represents 1, 2 or 3.

In formula (10), which represents a carbonylmethylene heterocycliccompound having a trihalogenomethyl group, L⁷ represents a hydrogen atomor a group represented by formula —CO—(R⁴⁷)_(q)(C(X⁴)₃)_(r), Qrepresents a sulfur atom, a selenium atom, an oxygen atom, adialkylmethylene group, an alken-1,2-ylene group, a 1,2-phenylene groupor —N(—R⁴⁸)—, M⁴ represents a substituted or unsubstituted alkylenegroup, a substituted or unsubstituted alkenylene group or a 1,2-arylenegroup, R⁴⁸ represents an alkyl group, an aralkyl group or an alkoxyalkylgroup, R⁴⁷ represents a divalent carbocyclic or heterocyclic aromaticgroup, X⁴ represents a chlorine atom, a bromine atom or an iodine atom,q represents 0 or 1, and r represents 1 or 2, provided that when qrepresents 0, r represents 1, and when q represents 1, r represents 1 or2.

In formula (11), which represents a4-halogeno-5-(halogenomethylphenyl)oxazole derivative, X⁵ represents ahalogen atom, t represents an integer of 1 to 3, s represents an integerof 1 to 4, R⁴⁹ represents a hydrogen atom or —CII_(3−t)X⁵ _(t) and R⁵⁰represents an s-valent unsaturated organic residue, which may besubstituted.

In formula (12), which represents a2-(halogenomethylphenyl)-4-halogenooxazole derivative, X⁶ represents ahalogen atom, v represents an integer of 1 to 3, u represents an integerof 1 to 4, R⁵¹ represents a hydrogen atom or —CH_(3−v)X⁶ _(v), and R²represents an u-valent unsaturated organic residue, which may besubstituted.

Specific examples of the compound having a carbon-halogen bond includecompounds described in Wakabayashi et al., Bull. Chem. Soc. Japan, Vol.42, 2924 (1969), for example,2-phenyl-4,6-bis(trichloromethyl)-S-triazine,2-(p-chlorophenyl)-4,6-bis(trichloromethyl)-S-triazine,2-(p-tolyl)-4,6-bis(trichloromethyl)-S-triazine,2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-S-triazine,2-(2′,4′-dichlorophenyl)-4,6-bis(trichloromethyl)-S-triazine,2,4,6-tris(trichloromethyl)-S-triazine,2-methyl-4,6-bis(trichloromethyl)-S-triazine,2-n-nonyl-4,6-bis(trichloromethyl)-S-triazine and2-(α,α,β-trichloroethyl)-4,6-bis(trichloromethyl)-S-triazine. Further,compounds described in British Patent 1,388,492, for example,2-styryl-4,6-bis(trichloromethyl)-S-triazine,2-(p-methylstyryl)-4,6-bis(trichloromethyl)-S-triazine,2-(p-methoxylstyryl)-4,6-bis(trichloromethyl)-S-triazine and2-(p-methoxylstyryl)-4-amino-6-trichloromethyl-S-triazine, compoundsdescribed in JP-A-53-133428, for example,2-(4-methoxynaphth-1-yl)-4,6-bis(trichloromethyl)-S-triazine,2-(4-ethoxynaphth-1-yl)-4,6-bis(trichloromethyl)-S-triazine,2-[4-(2-ethoxyethyl)naphth-1-yl]-4,6-bis(trichloromethyl)-S-triazine,2-(4,7-dimethoxynaphth-1-yl)-4,6-bis(trichloromethyl)-S-triazine and2-(acenaphth-5-yl)-4,6-bis(trichloromethyl)-S-triazine, and compoundsdescribed in German Patent 3,337,024, for example, the compounds shownbelow are exemplified. Moreover, compounds which can be easilysynthesized by one skilled in the art according to synthesis methodsdescribed in M. P. Hutt, E. F. Elslager and L. M. Herbel, Journal ofHeterocyclic Chemistry, Vol. 7, No. 3, page 511 et seq. (1970), forexample, the compounds shown below are exemplified.

(l) Azo Series Compound

The azo series compound (1) preferably used as the radical initiator inthe invention includes, for example, 2,2′-azobisisobutyronitrile,2,2′-azobispropionitrile, 1,1′-azobis(cyclohexane-1-carbonitrile),2,2′-azobis(2-methylbutyroritile),2,2′-azobis(2,4-dimethylvaleronitrile),2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile),4,4′-azobis(4-cyanovaleric acid), dimethyl 2,2′-azobisisobutyrate,2,2′-azobis(2-methypropionamidooxime),2,2′-azobis[2-(2-imidazolin-2-yl)propane],2,2′-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide},2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide],2,2′-azobis(N-butyl-2-methylpropionamide),2,2′-azobis(N-cyclohexyl-2-methylpropionamide),2,2′-azobis[N-(2-propenyl)-2-methylpropionamide] and2,2′-azobis(2,4,4-trimethylpentane).

More preferable examples of the radical initiator for use in theinvention include the above-described aromatic ketone (a), onium saltcompound (b), organic peroxide (c), hexaarylbiimidazole compound (e),metallocene compound (i) and compound having a carbon-halogen bond (k),and most preferable examples of the radical initiator include thearomatic iodonium salt, aromatic sulfonium salt, titanocene compound andtrihalomethyl-S-triazine compound represented by formula (6) describedabove.

The initiator can be added to the laser-decomposable resin compositioncontaining the polymerizable compound ordinarily from 0.1 to 50% byweight, preferably from 0.5 to 30% by weight, particularly preferablyfrom 5 to 20% by weight, based on tie total solid content of thepolymerizable composition.

The initiators can be preferably used individually or in combination oftwo or more thereof in the invention.

Other Components

To the laser-decomposable resin composition according to the invention,other components suitable for the use and production method thereof mayfurther be appropriately added. Preferable examples of the additive aredescribed below.

<Sensitizing Dye>

In the case wherein the exposure is conducted using as a light source, alaser (for example, YAG laser or semiconductor laser) emitting aninfrared ray of 760 to 1,200 nm, an infrared absorbing agent isordinarily used. The infrared absorbing agent absorbs a laser beam andgenerates heat to accelerate thermal decompositions. The infraredabsorbing agent for use in the invention includes a dye and pigment eachhaving an absorption maximum in a wavelength range of 760 to 1,200 nm.

As the dye, commercially available dyes and known dyes described inliteratures, for example, Senryo Binran (Dye Handbook) compiled by TheSociety of Synthetic Organic Chemistry, Japan (1970) can be used.Specifically, the dye includes azo dyes, metal complex azo dyes,pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes,phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes,cyanine dyes, squarylium dyes, pyrylium salts and metal thiolatecomplexes.

Examples of preferable dye include cyanine dyes described, for example,in JP-A-58-125246, JP-A-59-84356, JP-A-59-202829 and JP-A-60-78787,methine dyes described, for example, in JP-A-58-173696, JP-A-58-181690and JP-A-58-194595, naphthoquinone dyes described, for example, inJP-A-58-112793, JP-A-58-224793, JP-A-59-48187, JP-A-59-73996,JP-A-60-52940 and JP-A-60-63744, squarylium dyes described, for example,in JP-A-58-112792, and cyanine dyes described, for example, in BritishPatent 434,875.

Also, near fared absorbing sensitzers described in U.S. Pat. No.5,156,938 are preferably used. Further, substitutedarylbenzo(thio)pyrylium salts described in U.S. Pat. No. 3,881,924,trimethinethiapyrylium salts described in JP-A-57-142645 (correspondingto U.S. Pat. No. 4,327,169), pyrylium compounds described inJP-A-58-181051, JP-A-58-220143, JP-A-59-41363, JP-A-59-84248,JP-A-59-84249, JP-A-59-146063 and JP-A-59-146061, cyanine dyes describedin JP-A-59-216146, pentamethinethopyrylium salts described in U.S. Pat.No. 4,283,475, and pyrylium compounds described in JP-B-5-13514 andJP-B-5-19702 are also preferably used. Other preferable examples of thedye include near infrared absorbing dyes represented by formulae (I) and(II) in U.S. Pat. No. 4,756,993.

Other preferable examples of the infrared absorbing dye according to theinvention include specific indolenine cyanine dyes described inJP-A-2002-278057.

Of the dyes, cyanine dyes, squarylium dyes, pyrylium dyes, nickelthiolate complexes and indolenine cyanine dyes are preferred. Further,cyanine dyes and indolenine cyanine dyes are more preferred.

Specific examples of the cyanine dye preferably used in the inventioninclude those described in Paragraph Nos. [0017] to [0019] ofJP-A-2001-133969, Paragraph Nos. [0012] to [0038] of JP-A-2002-40638 andParagraph Nos. [0012] to [0023] of J-A-2002-23360.

The dye represented by formula (d) or formula (e) shown below ispreferable from the standpoint of light-to-heat conversion property.

In formula (d), R²⁹ to R³² each independently represents a hydrogenatom, an alkyl group or an alkyl group. R³³ and R³⁴ each independentlyrepresents an alkyl group, a substituted oxy group or a halogen atom. nand m each independently represents an integer of 0 to 4. R²⁹ and R³¹ orR³³ and R³² may be combined with each other to form a ring. Also, R²⁹and/or R³⁰ and R³³ or R³¹ and/or R³² and R³⁴ may be combined with eachother to form a ring. Further, when plural R³³s or R³⁴s are present, theR³³s or R³⁴s may be combined with each other to form a ring. X² and X³each independently represents a hydrogen atom, an alkyl group or an arylgroup, provided that at least one of X² and X³ represents a hydrogenatom or an alkyl group. Q represents a trimethine group which may have asubstituent or a pentamethine group which may have a substituent or mayform a ring structure together with a divalent organic group. Zc⁻represents a counter anion. However, Zc⁻ is not necessary when the dyerepresented by formula (d) has an anionic substituent in the structurethereof and neutralization of charge is not needed. Preferable examplesof the counter ion for Zc⁻ include a halogen ion, a perchlorate ion, atetrafluoroborate ion, a hexafluorophosphate ion and a sulfonate ion,and particularly preferable examples thereof include a perchlorate ion,a hexafluorophosphate ion and an arylsulfonate ion in view of thepreservation stability of a coating solution for resin compositionlayer.

Specific examples of the dye represented by formula (d) preferably usedin the invention include those illustrated below.

In formula (e) R³⁵ to R⁵⁰ each independently represents a hydrogen atom,a halogen atom, a cyano group, an alkyl group, an aryl group, an alkenylgroup, an alkynyl group, a hydroxy group, a carbonyl group, a thiogroup, a sulfonyl group, a sulfinyl group, an oxy group, an amino groupor an onium salt structure. When a substituent can be introduced intothese groups, they may live the substituent. M represents two hydrogenatoms, a metal atom, a halometal group or an oxymetal group. Examples ofthe metal atom included therein include atoms of Groups IA, IIA, IIIBand IVB of the Periodic Table, transition metals of the first, secondand third period, and lanthanoid elements. Among them, copper,magnesium, iron, zinc, cobalt, aluminum, titanium and vanadium arepreferred.

Specific examples of the dye represented by formula (e) preferably usedin the invention include those illustrated below.

Examples of the pigment for use in the invention include commerciallyavailable pigments and pigments described in Colour Index (C.I.),Saishin Ganryo Binran (Handbook of the Newest Pigments) compiled byPigment Technology Society of Japan (1977), Saishin Ganryo Oyou Gijutsu(Newest Application on Technologies for Pigments), CMC Publishing Co.,Ltd. (1986) and Insatsu Ink Gijutsu (Printing Ink Technology), CMCPublishing Co., Ltd. (1984).

Examples of the pigment include black pigments, yellow pigments, orangepigments, brown pigments, red pigments, purple pigments, blue pigments,green pigments, fluorescent pigments, metal powder pigments andpolymer-bonded dyes. Specific examples of usable pigment includeinsoluble azo pigments, azo lake pigments, condensed azo pigments,chelated azo pigments, phthalocyanine pigments, anthraquinone pigments,perylene and perynone pigments, thioindigo pigments, quinacridonepigments, dioxazine pigments, isoindolinone pigments, quinophithalonepigments, dying lake pigments, azine pigments, nitroso pigments, nitropigments, natural pigments, fluorescent pigments, inorganic pigments andcarbon black. Of the pigments, carbon black is preferred.

The pigment may be used without undergoing surface treatment or may beused after tie surface treatment. For the surface treatment, a method ofcoating a resin or wax on the surface, a method of attaching asurfactant and a method of bonding a reactive substance (for example, asilane coupling agent, an epoxy compound or polyisocyanate) to thepigment surface. The surface treatment methods are described in KinzokuSekken no Seishitsu to Oyo (Properties and Applications of Metal Soap),Saiwai Shobo, Insatsu Ink Gijutsu (Printing Ink Technology), CMCPublishing Co., Ltd. (1984), and Saishin Ganryo Oyo Gijutsu (NewestApplication on Technologies for Pigments), CMC Publishing Co., Ltd.(1986).

The pigment has a particle size of preferably from 0.01 to 10 μm, morepreferably from 0.05 to 1 μm, particularly preferably from 0.1 to 1 μm.When the particle size of the pigment is 0.01 μm or more, stability ofthe pigment dispersion in a coating solution increases and when it is 10μm or less, uniformity of the resin composition layer is good.

For dispersing the pigment, a known dispersion technique for use in theproduction of ink or toner may be used. Examples of the dispersingmachine include an ultrasonic dispersing machine, a sand mill, anattritor, a pearl mill, a super-mill, a ball mill, an impeller, adisperser, a KD mill, a colloid mill, a dynatron, a three roll mill anda pressure kneader. The dispersing machines are described in detail inSaishin Ganryo Oyo Gijutsu (Newest Application on Technologies forPigments), CMC Publishing Co., Ltd. (1986).

<Co-Sensitizer>

The sensitivity at the photo-curing of the resin composition layer canbe further improved by using a certain additive (hereinafter referred toas a “co-sensitizer”). The operation mechanism of the co-sensitizer isnot quite clear but may be considered to be mostly based on thefollowing chemical process. Specifically, the co-sensitizer reacts withvarious intermediate active species (for example, a radical or a cation)generated during the process of photo-reaction initiated by thephotopolymerization initiator and subsequent addition-polymerizationreaction to produce new active radicals. The co-sensitizers are roughlyclassified into (a) compound which is reduced to produce an activeradical, (b) compound which is oxidized to produce an active radical and(c) compound which reacts with a radical having low activity to convertit into a more highly active radical or acts as a chain transfer agent.However, in many cases, a common view about which an individual compoundbelongs to which type is not present.

(a) Compound Which is Reduced to Produce an Active Radical

Compound Having Carbon-Halogen Bond:

An active radical is considered to be generated by the reductivecleavage of the carbon-halogen bond. Specific examples of the compoundpreferably used include a trihalomethyl-s-triazine and atrihalomethyloxadiazole.

Compound Having Nitrogen-Nitrogen Bond:

An active radical is considered to be generated by the reductivecleavage of the nitrogen-nitrogen bond. Specific examples of thecompound preferably used include a hexaaylbiimidazole.

Compound Having Oxygen-Oxygen Bond:

An active radical is considered to be generated by the reductivecleavage of the oxygen-oxygen bond. Specific examples of the compoundpreferably used include an organic peroxide.

Onium Compound:

An active radical is considered to be generated by the reductivecleavage of a carbon-hetero bond or oxygen-nitrogen bond. Specificexamples of the compound preferably used include a diarryliodonium salt,a triarylsulfonium salt and an N-alkoxypyrdinium (azinium) salt.

Ferrocene and Iron-Arene Complexes:

An active radical can be reductively generated.

(b) Compound Which is Oxidized to Produce an Active Radical

Alkylate Complex:

An active radical is considered to be generated by the oxidativecleavage of a carbon-hetero bond. Specific examples of the compoundpreferably used include a triaryl alkyl borate.

Alkylamine Compound:

An active radical is considered to be generated by the oxidativecleavage of a C—X bond on the carbon adjacent to nitrogen, wherein X ispreferably a hydrogen atom, a carboxyl group, a trimethylsilyl group ora benzyl group. Specific examples of the compound include anethanolamine, an N-phenylglycine and an N-trimethylsilylmethylaniline.

Sulfur-Containing or Tin-Coating Compound:

A compound in which the nitrogen atom of the above-described aminecompound is replaced by a sulfur atom or a tin atom is considered togenerate an active radical in the same manner. Also, a compound havingan S—S bond is known to effect sensitization by the cleavage of the S—Sbond.

α-Substituted Methylcarbonyl Compound:

An active radical can be generated by he oxidative cleavage ofcarbonyl-α-carbon bond. The compound in which the carbonyl is convertedinto an oxime ether also shows the similar function. Specific examplesof the compound include an2-alkyl-1-[4-(alkylthio)phenyl]-2-morpholinopronone-1 and an oxime etherobtained by a reaction of the2-alkyl-1-[4-(alkylthio)phenyl]-2-morphoinopronone-1 with a hydroxyamineand subsequent etherification of the N—OH.

Sulfinic Acid Salt:

An active radical can be reductively generated. Specific examples of thecompound include sodium arylsulfinate.

(c) Compound Which Reacts with a Radical to Convert it into a MoreHighly Active Radial or Acts as a Chain Transfer Agent:

For example, a compound having SH, PH, SiH or GeH in its molecule isused as the compound which reacts with a radical to convert it into amore highly active radical or acts as a chain transfer agent. Thecompound donates hydrogen to a low active radical species to generate aradical or is oxidized and deprotonized to generate a radical. Specificexamples of the compound include a 2-mercaptobenzothiazole, a2-mercaptobenzoxazole and a 2-mercaptobenzimidazole.

A large number of examples of the co-sensitizer are more specificallydescribed, for example, in JP-A-9-236913 as additives for the purpose ofincreasing sensitivity, and they can be used in the invention. Some ofthem are set forth below, but the invention should not be construed asbeing limited thereto. In the formulae below, -TMS indicates atrimethylsilyl group.

Similarly to the above-described sensitizing dye, the co-sensitizer canbe subjected to various chemical modifications so as to improve thecharacteristics of the resin composition layer. For instance, methods,for example, binding to the sensitizing dye, initiator compound,addition-polymerizable unsaturated compound or other part introductionof a hydrophilic site, introduction of a substituent for improvingcompatibility or inhibiting deposition of crystal, introduction of asubstituent for improving an adhesion property, and formation of apolymer, may be used.

The co-sensitizers may be used individually or in combination of two ormore thereof. The amount of the co-sensitizer used is ordinarily from0.05 to 100 parts by weight, preferably from 1 to 80 parts by weight,more preferably from 3 to 50 parts by weight, per 100 parts by weight ofthe polymerizable compound having an ethylenically unsaturated doublebond.

<Polymerization Inhibitor>

It is preferred to add a small amount of a thermal polymerizationinhibitor to the resin composition according to the invention inaddition to the above-described components, in order to preventundesirable thermal polymerization of the polymerizable compound havingan ethylenically unsaturated double bond during the production orpreservation of the resin composition. Suitable examples of the thermalpolymerization inhibitor include hydroquinone, p-methoxyphenol,di-tert-butyl-p-cresol, pyrogallol, tert-butylcatechol, benzoquinone,4,4′-thiobis(3-methyl-6-tert-butylphenol),2,2′-methylenebis(4-methyl-6-tert-butylphenol) andN-nitrosophenylhydroxyamine cerium(III) salt. Also, as thepolymerization inhibitor, Q-1301 (10% tricresyl phosphate solution,produced by Wako Pure Chemical Industries, Ltd.) is preferable becauseof extremely excellent stability at the preservation of a layer orpattern-forming material prepared by using the resin compositionaccording to the invention. When is compound is used in combination withthe above-described urethane type addition polymerizable compound,particularly, PLEX 6661-0 (produced by Degussa GmbH), the dramaticallyexcellent preservation stability of the layer or pattern-formingmaterial and the good laser engraving sensitivity can be obtained. Theamount of the thermal polymerization inhibitor added is preferably fromabout 0.01 to about 5% by weight based on the total resin composition.In order to avoid polymerization inhibition due to oxygen, a higherfatty acid derivative, for example, behenic acid or behenic amide may beadded and allowed to localize on the resin composition layer surfaceduring the drying step after the coating thereof on a support, ifdesired. The amount of the higher fatty acid derivative added ispreferably from about 0.5 to about 10% by weight based on the totalresin composition.

<Coloring Agent>

A coloring agent, for example, a dye or a pigment may further be addedfor the purpose of coloring the resin composition layer. By thecoloring, properties, for example, visibility of the image area oraptitude for an image density measurement apparatus can be improved. Apigment is preferably used as the coloring agent. Specific examples thecoloring agent include a pigment, for example, a phthalocyanine pigment,an azo pigment carbon black or titanium oxide, and a dye, for example,Ethyl Violet, Crystal Violet, an azo dye, an athraquinone dye or acyanine dye. The amount of the coloring agent added is preferably fromabout 0.5 to about 5% by weight based on the total resi cmposition.

<Other Additives>

Further, known additives, for example, a filler or a plasticizer may beadded for improving physical properties of the cured layer.

The filler may be an organic compound, an inorganic compound or amixture thereof. Examples of the organic compound include carbon black,carbon nanotube, fullerene and graphite. Examples of the inorganiccompound include silica, alumina aluminum and calcium carbonate.

Examples of the plasticizer include dioctyl phthalate, didodecylphtlalate, triethylene glycol dicaprylate, dimethyl glycol phthalate,tricresyl phosphate, dioctyl adipate, dibutyl sebacate and triacetylglycerol. In the case of using a binder, the plasticizer can be added inan amount of 10% by weight or less based on the total weight of thecompound having an ethylenically unsaturated double bond and the binder.

Of the plasticizers, since not only the flexibility of the layer orpattern-forming material prepared from the resin composition accordingto the invention becomes very well and the aptitude for a flexographicprinting plate increases but also the engraving sensitivity increases, apolyethylene glycol and a polypropylene glycol (monool type or dioltype) are preferable. A polypropylene glycol (monool type or diol type)is more preferable, and a polypropylene glycol (diol type, averagemolecular weight: 1,000) is particularly preferable. When thepolypropylene glycol (monool type or diol type) plasticizer is used incombination with the above-described urethane type additionpolymerizable compound, particularly, PLEX 6661-0 (produced by DegussaGmbH), the above described excellent characteristics become prominent.

(Formation of Film)

In order to mold the laser-decomposable resin composition according tothe invention into a sheet form, a roll form or a cylindrical form, amolding method for conventional resin can be used. For example, acasting method, a method of extruding the resin composition from anozzle or dies using a machine, for example, a pump or an extruder andadjusting the thickness by a blade or by calendering with a roller isexemplified. In such case, it is also possible to perform the moldingaccompanied with heating within a range wherein the performance of theresin composition is not damaged. Also, a rolling treatment, a grindingtreatment or the like may be carried out, if desired. Ordinarily, theresin composition is molded on an underlay referred to as a back filmcomposed of a material, for example, PET or nickel in many cases.Further, a cylindrical support made of fiber reinforced plastic (FRP),plastic or metal can also be used. As the cylindrical support, a hollowcylindrical support having a constant thickness can be used for thepurpose of weight saving. The role of the back film or cylindricalsupport is to ensure the dimensional stability of molding. Therefore, amaterial with high dimensional stability should be selected. Specificexamples of the material include a crystalline resin, for example, apolyester resin, a polyimide resin, a polyamide resin, polyamideimideresin, a polyetherimide resin, polybismaleimide resin, a polysulfoneresin, a polycarbonate resin, a polyphenyleneether resin, apolyphenylenethioether resin, a polyethersulfone resin or a fullaromatic polyester resin, a full aromatic polyamide resin and an epoxyresin. Further, the resins may be used in the form of laminate. Forexample, a sheet composed of a full aromatic polyamide film having athickness of 4.5 μm both surfaces of which are laminated with apolyethylene terephthalate layer having a thickness of 50 μm isexemplified. Moreover, a porous sheet, for example, a cloth formed byknitting of fiber, a nonwoven cloth or a film having fine pores can beused as the back film. In the case of using a porous sheet as the backfilm, when the resin composition is impregnated into the pores of theporous sheet and subjected to light curing, a high adhesive property canbe achieved by means of integration of the cured resin layer and theback film. Examples of the fiber for the formation of cloth or nonwovencloth include, an inorganic fiber, for example, a glass fiber, aluminafiber, a carbon fiber, an alumina-silica fiber, a boron fiber, a highsilicon fiber, a potassium titanate fiber or a sapphire fiber, a naturalfiber, for example, cotton or hemp, a semisynthetic fiber, for example,rayon or acetate, and a synthetic fiber, for example, nylon, polyester,acryl, vinylon, polyvinyl chloride, polyolefin, polyurethane, polyimideor aramide. Furthermore, cellulose produced by a bacterium is a highcrystalline nanofiber and a material capable of forming a thin andhighly dimensionally stable nonwoven fiber.

<Pattern-Forming Material>

The pattern-forming material according to the invention means apattern-forming material wherein based on laser exposure, the exposedarea forms a concave portion in comparison with the unexposed area,whereby a concavo-convex pattern is formed. Therefore, it includes notonly a pattern-forming material of type wherein the concave portion isdirectly (for example, by ablation) formed by the laser exposure butalso a pattern-forming material of type wherein the concave portion isformed by conducting heating treatment or development processing with anaqueous alkali solution or the like after the laser exposure. Thepattern-forming material according to the invention is particularlypreferably used as the pattern-forming material of the former type.

As for the pattern-forming material according to the invention the usethereof is not particularly restricted, as long as the above-describedcharacteristic is fulfilled, and it can be utilized over a wide range,for instance, in a printing plate precursor, for example, forlithographic printing, gravure printing, letterpress or screen printing,a printed circuit board, a photoresist material for semiconductor and arecording material for optical disc. Above all, the pattern-formingmaterial is preferably used as a printing plate precursor for directplate-making by engraving with laser, so-called “laser engraving”. Inparticular, it is preferably used as a flexographic printing plateprecursor and a flexographic printing plate precursor for laserengraving is a most preferable use for the pattern-forming materialaccording to the invention.

The pattern-forming material according to the invention comprises asupport having thereon at least one heat-decomposable resin layer(hereinafter, also referred to as a pattern-forming layer).

According to a first embodiment of the pattern-forming material of theinvention, the pattern-forming material is characterized by having aheat-decomposable resin layer comprising the laser-decomposable resincomposition according to the invention on a support. Theheat-decomposable resin layer may contain the above-describedpolymerizable compound, initiator and other components, if desired, inaddition to the specific polyurethane resin.

According to a second embodiment of the pattern-forming material of theinvention, the pattern-forming material is characterized by having atleast two heat-decomposable resin layers on a support wherein a resinconstituting the heat-decomposable resin layer close to the support isthe specific polyurethane resin according to the invention.Specifically, the pattern-forming material is characterized in that thepattern-forming layer comprises a construction of two or more layers(hereinafter, also referred to as a multilayer construction) and has afirst layer close to the support (hereinafter, also referred to as anlower layer) and a second layer positioned above the first layer(hereinafter, also referred to as an upper layer) and in that as a resinconstituting the lower layer is used the specific polyurethane resinaccording to the invention. The upper limit of number of thepattern-forming layers is not particularly restricted.

The specific polyurethane resin used in the lower layer has a feature inthat the heat decomposition temperature thereof is relatively low (nothigher than 250° C.).

The term “heat decomposition temperature of resin” as used herein meanstemperature at which decrease of weight resulting from the heatdecomposition of resin initiates in TGA (thermogravimetic analysis)measurement. Specifically, the measurement of heat decompositiontemperature of resin can be performed in the following manner. Morespecifically, 7 mg of the resin was heated from 30 to 500° C. at atemperature rising rate of 10° C./minute using a thermogravimetricapparatus (produced by TA Instruments Japan Co., Ltd.) to determine heatdecomposition initiation temperature and the temperature obtained isconsidered as the heat decomposition temperature of the resin. The term“heat decomposition initiation temperature” as used herein meanstemperature at which decrease of weight resulting from the heatdecomposition of the resin initiates while the resin has been heated.

In general, temperature elevation of the pattern-forming layer due tolaser irradiation gradually decreases in the direction of thickness ofthe layer and temperature becomes relatively low in the neighborhood ofsupport. However, in the laser-decomposable pattern-forming materialaccording to the second embodiment of the invention, it is believed thatsince the heat decomposition temperature of the resin of the lower layeris low, the heat decomposition of the resin is apt to occur under thecircumstances and as a result, the laser decomposability (laserengraving property) increases to achieve high sensitivity.

The lower layer of laser-decomposable pattern-forming material maycontain other rein, if desire, in addition to the above-describedspecific polyurethane resin. Examples of the other resin include thebinder polymer described above with respect to the laser-decomposableresin composition. Further, if desired, the lower layer may containadditives, for example, the polymerizable compound (monomer), initiatorand other components described above with respect to thelaser-decomposable resin composition.

It is desirable that such other resin and additives are used within therange wherein the heat decomposability of the lower layer is notimpaired. From this point of view, a ratio of the polyurethane resin/theother components than the polyurethane resin is preferably from 50/50 to100/0 (by weight), more preferably from 70/30 to 100/0 (by weight), andparticularly preferably 100/0 (by weight).

Now, the upper layer of the laser-decomposable pattern-forming layersaccording to the second embodiment of the invention is described below.

The upper layer may be any layer comprising a laser-decomposable resincomposition and ordinarily contains additives, for example, apolymerizable compound (monomer), initiator and other components inaddition to a binder polymer.

Examples of the binder polymer for use in the upper layer include thebinder polymer described above with respect to the laser-decomposableresin composition. The amount of the binder polymer added is ordinarilyfrom 1 to 99% by weight, preferably from 5 to 80% by weight, based onthe total solid content of the upper layer. The binder polymer may alsoused together with the conventional resin described above with respectto the laser-decomposable resin composition.

The amount of the resin used together is ordinarily from 1 to 90% byweight, preferably from 5 to 80% by weight, based on the binder polymerdescribed above.

It is preferred that the resin constituting the upper layer has heatdecomposition temperature higher than the heat decomposition temperatureof the specific polyurethane resin constituting the lower layer. Fromthe standpoint of laser decomposability (laser engraving property), thedifference of heat decomposition temperatures is preferably 80° C. ormore, more preferably 100° C. or more, and particularly preferably 150°C. or more.

With respect to the polymerizable compound (monomer), initiator, otheradditives and the like for use in the upper layer, those described forthe laser-decomposable resin composition described above areexemplified, respectively.

(Support)

A material having flexibility and excellent dimensional stability ispreferably used as the support of the pattern-forming material in theinvention. Examples of the support include a polyethylene terephthalatefilm, a polyethylene naphthalate film, a polybutylene terephthalate filmand a polycarbonate film. The thickness of the support is preferablyfrom 50 to 350 μm and more preferably from 100 to 250 μm from thestandpoint, for example, of mechanical characteristics, shape stabilityand handling property of the pattern-forming material. Also, in order toincrease adhesion between the support and the pattern-forming layer, aknown adhesive layer conventionally used for such a purpose may beprovided on the surface of the support, if desired.

Further, the adhesion property to the pattern-forming layer or theadhesive layer can be improved by conducting physical or chemicaltreatment on the surface of support used in the invention. Examples ofthe physical treatment include a sand blast method, a wet sand blastmethod spraying liquid containing fine particles, a corona dischargetreatment method, a plasma treatment method or an ultraviolet ray orvacuum ultraviolet ray irradiation treatment method. Examples of thechemical treatment include a strong acid treatment method, a strongalkali treatment method, an oxidant treatment method and a couplingagent treatment method.

(Patter-Forming Layer)

The patter-forming layer according to the invention is preferablyprepared, for example, by a method of dissolving the constitutingcomponents of the layer in a solvent and coating on a support, followedby drying or a method of kneading the constituting components of thelayer by a kneader and casting on a support. In order to prepare aplurality of patter-forming layers, a method wherein the components ofeach layer were dissolved in a solvent and the lower layer is coated ona support, followed by drying and the upper layer is coated on the lowerlayer, followed by drying or a method wherein the components of eachlayer were kneaded by a kneader and casting successively on a support ispreferably used.

It is preferred at the pattern-forming layer according to the inventionis cured by crosslinking polymerization) before the decomposition withlaser from the standpoint of increasing the strength of layer. In orderto cure the layer, it is preferred to incorporate the polymerizablecompound as described above into the layer. This method is ordinarilyemployed as a means for increasing the strength of layer in anegative-type (polymerization type) photosensitive material, and it isbelieved that the similar result can also be achieved in the invention.

The method is particularly effective in the case wherein thepattern-forming material is a flexographic printing plate precursor forlaser engraving. By the curing before the laser engraving, advantagesare obtained in that a relief formed by the laser engraving becomessharp and in that tackiness of engraved scrap generated at the laserengraving can be restrained.

The method for curing the layer can be used without any particularlimitation as long as it is possible to cause polymerization reaction ofthe polymerizable compound, for example, to heat the layer, to irradiatethe layer with light or to incorporate a photo- or heat-polymerizationinitiator or the like into the layer and to perform light irradiation ofheating.

Among them, as the method for curing, the heating of the layer ispreferable in view of ease of operation. For the heating to causecrosslinking polymerization) of the layer before the laserdecomposition, any heating method, for example, an oven, a thermal head,a heating roll or a laser beam can be used. When the temperature controlis necessary, it can be performed by controlling the temperature of theoven, thermal head or heating roll or by controlling the intensity orspot diameter of the laser beam. The heating temperature is preferablyfrom 40 to 250° C., more preferably from 60 to 220° C., and sill morepreferably from 80 to 200° C., from the standpoint of thermal stabilityof the coexisting organic compound.

The thickness of the pattern-forming layer (total thickness of the lowerlayer and the upper layer in the case of a multilayer construction) isordinarily from 0.0005 to 10 mm, and preferably from 0.005 to 7 mm.

The thickness of the layer for use in the laser engraving can beappropriately determined depending on the purpose of utilization. Thethickness is preferably in a range of 0.05 to 10 mm, and more preferablyin a range of 0.1 to 7 mm.

A ratio of the thickness of lower layer/upper layer is preferably in arange of 30/70 to 95/5, more preferably in a range of 50/50 to 95/5, andparticularly preferably in a range of 70/30 to 90/10.

In some cases, the layers having different compositions may be multiplylaminated. As a combination of plural layers, for example, it ispossible to from a layer capable of undergoing engraving using a laserhaving an emitting wavelength in a near infrared region, for example, aYAG laser, a fiber laser or a semiconductor laser as the uppermost layerand under the layer, a layer capable of undergoing laser engraving usingan infrared laser, for example, a carbon dioxide gas laser or avisible-ultraviolet laser is formed. In the case of conducting the laserengraving of such laminate, different laser engraving apparatus equippedwith an infrared laser and a near infrared laser respectively can beemployed or one laser engraving apparatus equipped with both of aninfrared laser and a near infrared laser can be employed.

According to the invention, a cushion layer composed of a resin orrubber having cushioning property can be formed between the support andthe pattern-forming layer or between the pattern-forming layer and theadhesive layer. In the case of forming the cushion layer between thesupport and pattern-forming layer, a method of preparing the cushionlayer having an adhesive layer on one side and pasting the adhesivelayer side thereof onto the support is simple. After pasting thecushioning layer, the surface may be subjected to cutting and polishingto shape. In a simpler manner, a liquid adhesive composition is coatedon the support in a constant thickness and cured with light to from thecushion layer. It is preferable for the cushion layer to have thecushioning property that the hardness of the cushion layer cured withlight is low. The resin layer cured with light having the cushioningproperty may contain bubbles.

<Laser Engraving>

In the laser engraving, a relief image is formed on the pattern-formingmaterial by making digitalized data based on the image to be formed andoperating a laser equipment utilizing a computer.

As described above, the pattern-forming material for use in laserengraving is not particularly restricted, and the flexographic printingplate precursor for laser engraving is particularly preferably used.

The laser used in the laser engraving can be any laser as long as it isable to form a pattern by laser ablation of the pattern-formingmaterial. In order to carry out the engraving with high speed, a laserhaving a high power is desirable. One preferable example of the laser isa laser having an emitting wavelength in an infrared region or nearinfrared region, for example, a carbon dioxide gas laser, a YAG laser, asemiconductor laser or a fiber laser. Also, an ultraviolet laser havingan emitting wavelength in an ultraviolet region, for example, an excimerlaser, a YAG laser wavelength-converted to the third harmonic or thefourth harmonic or a copper vapor laser is also able to conduct ablationprocessing which cleaves a bond between molecules of organic compoundand thus is suitable for microfabrication. A laser having an extremelyhigh peak power, for example, a fermtosecond laser can also be employed.The laser irradiation may be performed continuously or pulsewise. As forthe flexographic printing plate precursor for laser engraving, a carbondioxide gas laser or a YAG laser is preferably used.

Although the engraving with laser is conducted under oxygen-containinggas, ordinarily in the presence of air or in airflow, it can beconducted under carbon dioxide gas or nitrogen gas. After the completionof the engraving, the powdery or liquid substance (scrap) occurred onthe surface of relief image can he removed by an appropriate method, forexample, a method of washing out, for example, with a solvent or watercontaining a surfactant, a method of spraying an aqueous cleaning agent,for example, by a high-pressure sprayer, a method of sprayinghigh-pressure steam, or a method of wiping off with cloth or the like.

The laser-decomposable resin composition according to the invention canbe applied to various usages, for example, a stamp, a seal, a designroll for embossing, a relief image for patterning an insulator, resistoror conductive paste used for the production of electronic components, arelief image for a mold material of ceramic materials, a relief imagefor display, for example, an advertising board or a sign board, or aprototype or matrix of various moldings, as well as the relief image.

It is also achieved to decrease tackiness on the surface of patternimage by forming a modifying layer on the surface of pattern image afterthe laser engraving. As the modifying layer, a coating treated with acompound reacting with the surface hydroxy group of the pattern image,for example, a silane coupling agent or a titanium coupling agent or apolymer film containing porous inorganic particles is exemplified. Thesilane coupling agent widely used is a compound having in its molecule afunctional group having high reactivity with the surface hydroxy groupof the pattern image. Examples of such a functional group include atrimethoxysilyl group, an triethoxysilyl group, a trichlorosilyl group,a diethoxysilyl group, a dimethoxysilyl group, a dichlorosilyl group, amonoethoxysilyl group, a monomethoxysilyl group and a monochlorosilylgroup. At least one of the functional groups is present in the moleculeof the compound and the compound is fixed on the surface of the patternimage by the reaction of the functional group with the surface hydroxygroup of the pattern image. Further, as the compound constituting thesilane coupling agent according to the invention, that having in itsmolecule at least one reactive functional group selected from anacryloyl group, a methacryloyl group, an active halogen-containing aminogroup, an epoxy group, a vinyl group, a perfluoroalkyl group and amercapto group or that having in its molecule a long chain alkyl groupis also used. When the coupling agent fixed on the surface hasparticularly a polymerizable reactive group in its molecule, the moresolid coating can be formed by irradiating the surface with light, heator an electron beam to form crosslinkage after the fixing the couplingagent on the surface.

EXAMPLES

The present invention will be described in more detail with reference tothe following examples, but the invention should not be construed asbeing limited thereto.

<Synthesis of Specific Polyurethane Resin>

Synthesis Example 1 Synthesis of Polyurethane Resin P-1

In a 500 ml 3-necked round-bottom flask equipped with a condenser and astirrer, 8.2 g (0.05 moles) of 2,2-bis(hydroxymethyl)butanoic acid and13.0 g (0.05 moles) of Diol compound (1) show below were dissolve in 100ml of N,N-dimethylacetamide. To the solution were added 25.5 g (0.102moles) of 4,4-diphenylmethane diisocyanate and 0.1 g of dibutyltindilaurate, and the mixture was heated at 100° C. for 8 hours withstirring. Then, the reaction mixture was diluted with 100 ml ofN,N-dimethylformamide and 200 ml of methyl alcohol and stirred for 30minutes. The reaction solution was poured into 3 liters of water withstirring to deposit a white polymer. The polymer was collected byfiltration, washed with water and dried under vacuum to obtain 37 g ofthe polymer.

As a result of measurement of a molecular weight by gel permeationchromatography (GPC), a weight average molecular weight (in terms ofstandard polystyrene) of the polymer was 95,000.

Synthesis Example 2 Synthesis of Polyurethane Resin P-5

In a 500 ml 3-necked round-bottom flask equipped with a condenser and astirrer, 5.9 g (0.04 moles) of 2,2-bis(hydroxymethyl)butanoic acid and15.9 g (0.06 moles) of Diol compound (2) shown below were dissolve in100 ml of N,N-diethylacetamide. To the solution were added 20.4 g (0.082moles) of 4,4-diphenylmethane isocyanate, 3.4 g (0.02 moles) of1,6-hexamethylene diisocyanate and 0.1 g of dibutyltin dilaurate, andthe mixture was heated at 100° C. for 8 hours with stirring. Then, thereaction mixture was diluted with 100 ml of N,N-dimethylformamide and200 ml of methyl alcohol and stirred for 30 minutes. The reactionsolution was poured into 3 liters of water wit stirring to deposit awhite polymer. The polymer was collected by filtration, washed withwater and dried under vacuum to obtain 34 g of the polymer.

As a result of measurement of a molecular weight by gel permeationchromatography (GPC), a weight average molecular weight (in terms ofstandard polystyrene) of the polymer was 99,000.

Synthesis Example 3 Synthesis of Polyurethane Resin P-6

In a 500 ml 3-necked round-bottom flask equipped with a condenser and astirrer, 5.4 g (0.04 moles) of 2,2-bis(hydroxymethyl)propionic acid and15.6 g (0.06 moles) of Diol compound (3) shown below were dissolve in100 ml of N,N-dimethylacetamide. To the solution were added 21.4 g(0.102 moles) of naphthalene diisocyanate and 0.1 g of dibutyltindilaurate, and the mixture was heated at 100° C. for 8 hours withstirring. Then, the reaction mixture was diluted with 100 ml ofN,N-dimethylformamide and 200 ml of methyl alcohol and stirred for 30minutes. The reaction solution was poured into 3 liters of water withstirring to deposit a white polymer. The polymer was collected byfiltration, washed with water and dried under vacuum to obtain 34 g ofthe polymer.

As a result of measurement of a molecular weight by gel permeationchromatography (GPC), a weight average molecular weight (in terms ofstandard polystyrene) of the polymer was 96,000.

Examples 1 to 14 and 1a and Comparative Examples 1 to 3

<Measurement of Heat Decomposition Initiation Temperature>

Seven milligrams of each of the resins (the specific polyurethane resinsaccording to the invention, a comparative polyurethane resin andcomparative resins) as sown in Table A below was heated from 30 to 500°C. at a temperature rising rate of 10° C./minute using athermogravimetric apparatus (produced by TA Instruments Japan Co. Ltd.)to determine heat decomposition initiation temperature. With respect toSpecific polyurethane resins P-37 and P-38, using 1 g of Specificpolyurethane resin P-37 or P-38, a 48% by weight methyl ethyl ketonesolution was prepared, the solution was cast on a glass petri dish anddried under a reduced pressure for 6 hours at 50° C. to remove methylethyl ketone, and the resulting solid was used as the sample formeasurement. The term “heat decomposition Initiation temperature” asused herein means temperature at which decrease of weight resulting fromthe heat decomposition of a sample initiates while the sample has beenheated. The results obtained are shown in Table A below. TABLE A HeatDecomposition Initiation Tem- Resin perature (° C.) Example 1 SpecificPolyurethane Resin P-1 229 Example 2 Specific Polyurethane Resin P-5 231Example 3 Specific Polyurethane Resin P-6 235 Example 4 SpecificPolyurethane Resin P-21 230 Example 5 Specific Polyurethane Resin P-29240 Example 6 Specific Polyurethane Resin P-30 240 Example 7 SpecificPolyurethane Resin P-31 245 Example 8 Specific Polyurethane Resin P-32210 Example 9 Specific Polyurethane Resin P-33 215 Example 10 SpecificPolyurethane Resin P-34 205 Example 11 Specific Polyurethane Resin P-35195 Example 12 Specific Polyurethane Resin P-36 185 Example 13 SpecificPolyurethane Resin P-37 244 Example 14 Specific Polyurethane Resin P-38258 Example 1a Specific Polyurethane Resin P-39 170 ComparativeComparative Polyurethane Resin CP-1 400 Example 1 ComparativeComparative Resin CP-2 412 Example 2 Comparative Comparative Resin CP-3410 Example 3Comparative Polyurethane Resin CP-1:

Polyurethane resin synthesized from Diisocyanate Compound (X) shownbelow and Diol Compound (Y) shown below (1:1 in molar ratio) (weightaverage molecular weight: 32,000)

Comparative Resin CP-2:

Styrene-butadiene block copolymer (trade name: TR2000, produced by JSRCorp) Comparative Resin CP-3:

Polymethyl methacrylate (weight average molecular weight: 21000,produced by Aldrich Corp.)

From the results shown in Table A, it is apparent that the resins in theexamples according to the invention exhibit the remarkably low heatdecomposition initiation temperature and excellent in the heatdecomposability in comparison with the resins in the comparativeexamples. These results indicate the effect of improving the heatdecomposability due to the specific polyurethane resin according to theinvention. Considering that the decrease in the heat decompositioninitiation temperature is not recognized as is apparent from thecomparison of the case wherein the polyurethane resin not containing anaromatic group as in Comparative Example 1 with the cases wherein theresin other than the polyurethane is used as in Comparative Examples 2and 3, it is highly surprising that the specific polyurethane resinaccording to the invention has such unique properties.

Examples 15 to 27 an Comparative Examples 4 to 5

<Preparation of Pattern-Forming Material>

The polyurethane resin, binder polymer, additive and laser absorber asshown in Table B below were mixed in a kneader for laboratory atmaterial temperature of 100° C. for 20 minutes to uniformly disperse thelaser absorber. The resulting mixture was then dissolved in toluenetogether with the polymerizable compound and initiator as shown in TableB below at 100° C., cooled to 40° C. and cast on a PET film having athickness of 125 μm. The film was dried in he atmosphere at roomtemperature for 48 hours and then dried at 90° C. for 1.5 hours.Thereafter, the relief layer (layer thickness: 1,000 μm) formed waslaminated to a PET film having a thickness of 125 μm coated with amixture of adhesion components. Thus, the relief layer was transferredto the PET film having a thickness of 125 μm coated with a mixture ofadhesion components. Then, the relief layer was heated using an overequipped with an exhaust system at normal pressure and at 180° C. for 20minutes to crosslink the relief layer. The crosslinking of the relieflayer was confirmed by observation of the disappearance of the peakderived from a carbon-carbon unsaturated bond using FT-IR. Thus, apattern-forming material was prepared. TABLE B Amount Composition ofPattern-Forming Layer (% by weight) Polyurethane resin (shown in TableC) Amount shown in Table C Binder polymer: Styrene-butadiene blockcopolymer Amount shown (trade name: TR2000, produced by JSR Corp.) inTable C Polymerizable compound: Hexanediol dimethacrylate 5.00Polymerizable compound: Lauryl acrylate 5.00 Initiator: Irugacure 369(produced by Ciba-Geigy Corp.) 1.00 Laser absorber: Finely dividedcarbon black 3.00 Additive (ozone degradation preventing wax): 1.001,4-Benzoquinone<Laser Engraving of Pattern-Forming Material>

Engraving by laser irradiation was performed using a high-grade CO₂Laser Marker ML-9100 Series (produced by Keyence Corp.) at 12 W and linespeed of 20 cm/sec with respect to a carbon dioxide (CO₂) laser or usinga Marker Engine 3000 (produced by Laserfront Technologies, Inc.) at 10 Wand line speed of 10 cm/sec with respect to a Nd-YAG laser. Thedifference of height between the laser irradiation portion (concaveportion) and laser unirradiation portion was measured by ultra-deepprofile measuring microscope (VK-8500, produced by Keyence Corp.) toevaluate the depth of laser engraving. The results are shown in Table C.As the value of the depth of laser engraving is large, the laserengraving is preformed in higher sensitivity. TABLE C Amount ofPolyurethane Resin Binder Depth of Amount (% Polymer (% Kind ofEngraving Kind by weight) by weight) Laser (μm) Example 15 P-29 85.00 0CO₂ 300 Example 16 P-29 20.00 65.00 CO₂ 280 Example 17 P-30 85.00 0 CO₂310 Example 18 P-31 85.00 0 CO₂ 300 Example 19 P-32 85.00 0 CO₂ 330Example 20 P-32 20.00 65.00 CO₂ 300 Example 21 P-32 85.00 0 Nd-YAG 150Example 22 P-34 85.00 0 CO₂ 350 Example 23 P-35 85.00 0 CO₂ 380 Example24 P-35 20.00 65.00 CO₂ 355 Example 25 P-36 85.00 0 CO₂ 415 Example 26P-36 20.00 65.00 CO₂ 400 Example 27 P-36 85.00 0 Nd-YAG 185 ComparativeNone 0 85.00 CO₂ 195 Example 4 Comparative CP-1 85.00 0 Nd-YAG 50Example 5

From the results show in Table C, it is apparent that the resincompositions in the examples according to the invention exhibit thelarge depth of laser engraving in comparison with the resin compositionsin the comparative examples. It can be seen that the heatdecomposability of the resin composition increases and the laserengraving is performed in high sensitivity by using the specificpolyurethane resin according to the invention.

Examples 28 to 33 and 46 to 47 and Comparative Examples 6 to 9

<Preparation of Pattern-Forming Material>

The composition for pattern-forming layer shown in Table D below wascast in a frame (15 cm×15 cm) made of teflon adhered on a PET film(thickness: 0.2 mm) with a cellophane tape and dried in an oven at 40°C. for 3 hours to form a layer (thickness: 1.2 mm). The thickness of thelayer was controlled by scraping out the excess composition forpattern-forming layer run over from the frame with a horizontal metalruler. Then, using an ultrahigh pressure mercury lamp having an emissionwavelength in an ultraviolet region, one side (surface 1) of theresulting layer was overall exposed (exposure amount: about 1,500mJ/cm²) and then the opposite side (surface 2) of the resulting layerwas overall exposed (exposure amount: about 600 mJ/cm²) to prepare apattern-forming material. With respect to Specific polyurethane resinsP-37 and P-38, a 48% by weight methyl ethyl ketone solution of each ofSpecific polyurethane resins P-37 and P-38 was prepared and used. TABLED Composition of Pattern-Forming Layer Amount Resin (shown in Table E)100.9 g Polymerizable compound (shown in Table E) 24.4 g Methyl ethylketone 29.6 g Polypropylene glycol (average molecular weight: 1,000,24.4 g produced by Wako Pure Chemical industries, Ltd.) Initiator:Irugacure 184 (produced by Ciba-Geigy Corp.) 2.0 g Polymerizationinhibitor: N-nitrosophenylhydroxylamine 0.5 g aluminum salt (Q-1301: 10%tricresyl phosphate solution, produced by Wako Pure Chemical industries,Ltd.)<Laser Engraving of Pattern-Forming Material>

The laser engraving was performed on the surface 1 of thepattern-forming material in the same manner as in Examples 15 to 27 andthe depth of laser engraving was evaluated, The results are shown inTable E. TABLE E Polymerizable Kind of Depth of Resin Compound LaserEngraving (μm) Example 28 Specific PLEX 6661-0 CO₂ 540 PolyurethaneResin P-37 Example 29 Specific PLEX 6661-0 CO₂ 530 Polyurethane ResinP-38 Example 30 Specific M-1 CO₂ 450 Polyurethane Resin P-37 Example 31Specific PLEX 6661-0 Nd-YAG 190 Polyurethane Resin P-37 Example 32Specific PLEX 6661-0 Nd-YAG 190 Polyurethane Resin P-38 Example 33Specific M-1 Nd-YAG 140 Polyurethane Resin P-37 Example 46 Specific PLEX6661-0 CO₂ 580 Polyurethane Resin P-39 Example 47 Specific PLEX 6661-0Nd-YAG 220 Polyurethane Resin P-39 Comparative Comparative PLEX 6661-0CO₂ 270 Example 6 Resin CP-2 Comparative Comparative M-1 CO₂ 270 Example7 Resin CP-2 Comparative Comparative PLEX 6661-0 Nd-YAG 45 Example 8Resin CP-2 Comparative Comparative M-1 Nd-YAG 50 Example 9 Resin CP-2PLEX 6661-0 (produced by Degussa GmbH

Mixture of the following structural isomers

From the results shown in Table E, it is apparent that the resincompositions in the examples according to the invention exhibit thelarge depth of laser engraving in comparison with the resin compositionsin the comparative examples. It can be seen that by using the specificpolyurethane resin according to the invention, the heat decomposabilityof the resin composition increases and the laser engraving is performedin higher sensitivity when used together with the urethane typeaddition-polymerizable compound.

Examples 34 to 45 an Comparative Examples 10 to 15

<Preparation of Pattern-Forming Material>

One hundred grams of each of the resins (the specific polyurethaneresins according to the invention and comparative resins) as sown inTable F below was stirred in a kneader for laboratory at materialtemperature of 120° C. to melt, cooled to 70° C. and cast on a PET filmsupport having a thickness of 125 μm. The film was dried in theatmosphere at room temperature for 48 hours and then dried at 80° C. for3 hours to prepare a lower layer

The binder polymer, additive and laser absorber as shown in Table Gbelow were mixed in a kneader for laboratory at material temperature of120° C. for 15 minutes to uniformly disperse the laser absorber. Theresulting mixture was then dissolved in toluene together with thepolymerizable compound as shown in Table G below at 100° C., cooled to60° C. and cast on a PET film having a thickness of 125 μm. The film wasdried in the atmosphere at room temperature for 48 hours and then driedat 80° C. for 3 hours to prepare an upper layer. Then, the upper layerwas brought into close contact with the lower layer to form a laminateand the PET film of the upper layer was peeled off so that apattern-forming material having the lower layer (thickness: 0.94 mm) andthe upper layer (thickness: 0.20 mm) provided on the PET film supportwas prepared. TABLE F Difference of Heat Decomposition Resin of LowerLayer Temperature Heat between Upper Depth of Decomposition Layer andLower Kind of Engraving Kind Temperature (° C.) Layer (° C.) Laser (μm)Example 34 P-1 229 156 CO₂ 280 Example 35 P-5 231 154 CO₂ 285 Example 36P-6 235 150 CO₂ 290 Example 37 P-21 230 155 CO₂ 285 Example 38 P-29 240145 CO₂ 265 Example 39 P-30 240 145 CO₂ 260 Example 40 P-31 245 140 CO₂260 Example 41 P-32 210 175 CO₂ 310 Example 42 P-33 215 170 CO₂ 300Example 43 P-33 215 170 Nd-YAG 120 Example 44 P-35 195 190 CO₂ 325Example 45 P-36 185 200 CO₂ 340 Comparative CP-1 — — CO₂ 195 Example 10Singe Layer Comparative Lower — 75 CO₂ 220 Example 11 Layer: CP-2/ UpperLayer: CP-1 Comparative Lower — 12 CO₂ 195 Example 12 Layer: CP-3/ UpperLayer: CP-1 Comparative CP-1 — Nd-YAG 52 Example 13 Singe LayerComparative Lower 75 Nd-YAG 53 Example 14 Layer: CP-2/ Upper Layer: CP-1Comparative Lower 12 Nd-YAG 54 Example 15 Layer: CP-3/ Upper Layer: CP-1Comparative Resin CP-1:

Styrene-butadiene block copolymer (trade name: TR2000, produced by JSRCorp.)(Heat decomposition temperature: 412° C.)

Comparative Resin CP-2:

Aliphatic polyurethane resin synthesized from Diisocyanate Compound (X)shown below and Diol Compound (Y) shown below (1:1 in molar ratio)(weight average molecular weight: 32,000)(Heat decompositiontemperature: 337° C.)

Comparative Resin CP-3:

Styrene-isoprene-styrene block copolymer (produced by AldrichCorp.)(Heat decomposition temperature: 400° C.)

The heat decomposition temperature of the resin was obtained in thefollowing manner.

Seven milligrams of the resin was heated from 30 to 500° C. at atemperature rising rate of 10° C./minute using a thermogravimetricapparatus produced by TA Instruments Japan Co., Ltd.) to determine heatdecomposition initiation temperature. The value obtained was consideredas the heat decomposition temperature of the resin. The term “heatdecomposition initiation temperature” as used herein means temperatureat which decrease of weight resulting from the heat decomposition of theresin initiates while the resin has been heated. TABLE G AmountComposition of Pattern-Forming Layer (% by weight) Binder polymer:Styrene-butadiene block copolymer 80.00 (trade name: TR2000, produced byJSR Corp.) Polymerizable compound: Hexanediol dimethacrylate 14.00 Laserabsorber: Finely divided carbon black 5.00 Additive (ozone degradationpreventing wax): 1.00 1,4-Benzoquinone<Laser Engraving of Pattern-Forming Material>

Engraving by laser irradiation was performed using a high-grade CO₂Laser Marker ML-9100 Series (produced by Keyence Corp.) at 12 W and linespeed of 10 cm/sec with respect to a carbon dioxide (CO₂) laser or usinga Marker Engine 3000 (produced by Laserfront Technologies, inc.) at 10 Wand line speed of 10 cm/see with respect to a Nd-YAG laser. Thedifference of height between the laser irradiation portion (concaveportion) and laser unirradiation portion was measured by ultra-deepprofile measuring microscope (VK-8500, produced by Keyence Corp.) toevaluate the depth of laser engraving. The results are shown in Table F.As the value of the depth of laser engraving is large, the laserengraving is performed in higher sensitivity.

From the results shown in Table F, it is apparent that the examplesaccording to the invention exhibit the large depth of laser engraving incomparison with the comparative examples. It can be seen that the heatdecomposability of the resin increases and the laser engraving isperformed in high sensitivity by using the specific polyurethane resinaccording to the invention in the lower layer.

Further, it can be understood that the extent of increase in the depthof laser engraving when Examples 42 and 43 using the specificpolyurethane resin according to the invention in the lower layer arecompared with Comparative Examples 10 and 13 having the pattern-forminglayer composed of a single layer is extremely large in comparison withthe extent of increase in the depth of laser engraving when ComparativeExamples 11 and 14 using the polyurethane resin containing no aromaticgroup in the lower layer are compared with Comparative Examples 10 and13 having the pattern-forming layer composed of a single layer. Thesefacts illustrate the unique properties of the polyurethane resinincluding an aromatic group according to the invention which are highlysurprising.

This application is based on Japanese Patent application JP 2006-237784,filed Sep. 1, 2006, Japanese Patent application JP 2006-263213, filedSep. 27, 2006, and Japanese Patent application JP 2007-85986, filed Mar.28, 2007, the entire contents of which are hereby incorporated byreference, the same as if fully set forth herein.

Although the invention has been described above in relation to preferredembodiments and modifications thereof, it will be understood by thoseskilled in the art that other variations and modifications can beeffected in these preferred embodiments without departing from the scopeand spirit of the invention.

1. A laser-decomposable resin composition comprising a polyurethaneresin having a structure wherein an aromatic group is directly connectedto a urethane bond.
 2. The laser-decomposable resin composition asclaimed in claim 1, wherein the polyurethane resin is a polyurethaneresin comprising a urethane bond represented by the following formula(1):

wherein, R₁ and R₂ each independently represents a divalent organicgroup, provided that at least one of R₁ and R₂ is an aromatic group. 3.The laser-decomposable resin composition as claimed in claim 2, whereinR₂ in the formula (1) represents an aromatic group.
 4. Thelaser-decomposable resin composition as claimed in claim 23 wherein R₁and R₂ in the formula (1) each represents an aromatic group.
 5. Thelaser-decomposable resin composition as claimed in claim 1, wherein thepolyurethane resin further has a carbonate site.
 6. Thelaser-decomposable resin composition as claimed in claim 1, wherein thepolyurethane resin further has an acetal site.
 7. The laser-decomposableresin composition as claimed in claim 1, which further comprises apolymerizable compound.
 8. The laser-decomposable resin composition asclaimed in claim 1, which further comprises a binder polymer.
 9. Alaser-decomposable resin composition prepared by curing thelaser-decomposable resin composition as claimed in claim
 7. 10. Alaser-decomposable resin composition prepared by curing thelaser-decomposable resin composition as claimed in claim
 8. 11. Apattern-forming material comprising a support and a heat-decomposableresin layer comprising the laser-decomposable resin composition asclaimed in claim
 1. 12. A pattern-forming material comprising a supportand a heat-decomposable resin layer comprising the laser-decomposableresin composition as claimed in claim
 8. 13. A laser-decomposablepattern-forming material comprising a support, a first heat-decomposableresin layer and a second heat-decomposable resin layer provided in thisorder, wherein a resin constituting the first heat-decomposable resinlayer is a polyurethane resin having a structure wherein aromatic groupis directly connected to a urethane bond.
 14. The laser-decomposablepattern-forming material as claimed in claim 13, wherein heatdecomposition temperature of a resin constituting the secondheat-decomposable resin layer is higher than heat decompositiontemperature of the polyurethane resin having a structure wherein anaromatic group is directly connected to a urethane bond.
 15. Thelaser-decomposable pattern-forming material as claimed in claim 13,wherein the polyurethane resin is a polyurethane resin comprising aurethane bond represented by the following formula (1):

wherein, R₁ and R₂ each independently represents a divalent organicgroup, provided that at least one of R₁ and R₂ is an aromatic group. 16.The laser-decomposable pattern-forming material as claimed in claim 15,wherein R₂ in the formula (1) represents an aromatic group.
 17. Thelaser-decomposable pattern-forming material as claimed in claim 15,wherein R₁ and R₂ in the formula (1) each represents an aromatic group.18. The laser-decomposable pattern-forming material as claimed in claim13, wherein the polyurethane resin further has a carbonate site.
 19. Aflexographic printing plate precursor of laser engraving type comprisingthe laser-decomposable pattern-forming material as claimed in claim 11.